1 00:00:01,070 --> 00:00:03,278 Viewers like you make this program possible. 2 00:00:03,279 --> 00:00:05,350 Support your local PBS station. 3 00:00:13,565 --> 00:00:15,290 An iconic temple, 4 00:00:15,291 --> 00:00:18,810 the largest religious monument in the world, 5 00:00:18,811 --> 00:00:22,504 Angkor Wat is an enduring enigma. 6 00:00:22,505 --> 00:00:25,714 The engineering feat of Angkor Wat is unbelievable. 7 00:00:25,715 --> 00:00:28,372 In the heart of one of the greatest ancient cities 8 00:00:28,373 --> 00:00:30,063 ever built: Angkor. 9 00:00:30,064 --> 00:00:31,409 One of the largest, 10 00:00:31,410 --> 00:00:33,894 if not the largest, city in the world at the time. 11 00:00:33,895 --> 00:00:36,449 Home to over 1,000 temples. 12 00:00:36,450 --> 00:00:40,073 Each new king would try to outbuild the reign before 13 00:00:40,074 --> 00:00:43,007 and build a bigger and more impressive temple. 14 00:00:43,008 --> 00:00:45,630 But then, the temples and the city were engulfed 15 00:00:45,631 --> 00:00:47,011 by the jungle. 16 00:00:47,012 --> 00:00:50,601 It mysteriously was abandoned. 17 00:00:50,602 --> 00:00:52,086 Well, so the story goes. 18 00:00:53,536 --> 00:00:54,812 There are few clues... 19 00:00:54,813 --> 00:00:58,264 Almost every wooden remain-- 20 00:00:58,265 --> 00:01:00,369 and the vast majority of structures at Angkor 21 00:01:00,370 --> 00:01:01,681 were built in wood-- 22 00:01:01,682 --> 00:01:04,132 deteriorate very, very quickly. 23 00:01:04,133 --> 00:01:06,168 ...and many mysteries. 24 00:01:06,169 --> 00:01:08,377 The lack of bodies. 25 00:01:08,378 --> 00:01:11,139 One million people, not a bone, 26 00:01:11,140 --> 00:01:13,727 not a cremated remain. 27 00:01:13,728 --> 00:01:16,178 It's fascinating and frustrating. 28 00:01:16,179 --> 00:01:18,870 There's another story there, sitting underneath. 29 00:01:18,871 --> 00:01:22,460 Now archaeologists are using the latest technologies 30 00:01:22,461 --> 00:01:24,980 to reveal Angkor's hidden secrets... 31 00:01:24,981 --> 00:01:26,844 Sarah took the lidar data. 32 00:01:26,845 --> 00:01:28,363 She used some machine-learning algorithms. 33 00:01:28,364 --> 00:01:30,261 ...to see through the jungle... 34 00:01:30,262 --> 00:01:32,712 The lidar data is absolutely mind-blowing. 35 00:01:32,713 --> 00:01:34,783 It was all an engineered landscape. 36 00:01:34,784 --> 00:01:36,992 ...and look into the past... 37 00:01:36,993 --> 00:01:38,580 Really, like the pages of a history book. 38 00:01:38,581 --> 00:01:42,204 ...to find new evidence of a great civilization. 39 00:01:42,205 --> 00:01:43,723 They didn't just build Angkor Wat, 40 00:01:43,724 --> 00:01:45,207 which is a spectacular temple, right? 41 00:01:45,208 --> 00:01:48,176 Like, they were transforming the entire landscape. 42 00:01:48,177 --> 00:01:51,351 "Angkor: Hidden Jungle Empire," 43 00:01:51,352 --> 00:01:53,872 right now, on "NOVA." 44 00:02:11,545 --> 00:02:13,511 In the jungles of Cambodia, 45 00:02:13,512 --> 00:02:17,136 a spectacular ruin rises from the trees. 46 00:02:17,137 --> 00:02:20,381 This is Angkor Wat. 47 00:02:22,038 --> 00:02:23,694 A 900-year-old temple, 48 00:02:23,695 --> 00:02:26,421 filled with intricate carvings 49 00:02:26,422 --> 00:02:28,630 and mysterious figures. 50 00:02:28,631 --> 00:02:32,116 It is the largest religious monument in the world 51 00:02:32,117 --> 00:02:35,016 and a masterpiece of ancient engineering. 52 00:02:36,501 --> 00:02:40,331 The engineering feat of Angkor Wat is unbelievable. 53 00:02:40,332 --> 00:02:41,851 It's amazing. 54 00:02:43,473 --> 00:02:45,992 Angkor Wat is the centerpiece 55 00:02:45,993 --> 00:02:48,201 of the ancient city of Angkor, 56 00:02:48,202 --> 00:02:51,239 a marvel of vast infrastructure, 57 00:02:51,240 --> 00:02:54,552 built with a network of human-made canals 58 00:02:54,553 --> 00:02:56,830 and enormous reservoirs. 59 00:02:56,831 --> 00:03:01,249 Angkor was the heart of a wealthy and dynamic empire 60 00:03:01,250 --> 00:03:03,906 that thrived for 600 years. 61 00:03:03,907 --> 00:03:08,704 Then, around 1300, suddenly, the building stopped. 62 00:03:08,705 --> 00:03:12,052 This vast, ornate city was largely abandoned. 63 00:03:12,053 --> 00:03:13,227 Why? 64 00:03:14,297 --> 00:03:16,160 Archaeologists like Piphal Heng 65 00:03:16,161 --> 00:03:18,300 are trying to answer that question 66 00:03:18,301 --> 00:03:21,130 and to understand the people of Angkor. 67 00:03:21,131 --> 00:03:23,512 Monumental architecture like Angkor Wat 68 00:03:23,513 --> 00:03:25,100 has been its signature. 69 00:03:25,101 --> 00:03:27,827 When you talk about Angkor, it's monuments. 70 00:03:27,828 --> 00:03:30,795 Part of my archaeological endeavor 71 00:03:30,796 --> 00:03:34,109 is to understand Angkorians people's life. 72 00:03:34,110 --> 00:03:36,076 What did they do? 73 00:03:36,077 --> 00:03:39,114 What was the relationship between the people and the city, 74 00:03:39,115 --> 00:03:42,566 the relationship between the people and the temple? 75 00:03:42,567 --> 00:03:45,948 And how did that change through time? 76 00:03:52,370 --> 00:03:55,303 The ancient city of Angkor was one of the biggest 77 00:03:55,304 --> 00:03:57,408 pre-industrial cities in the world. 78 00:03:57,409 --> 00:04:00,584 Located in Cambodia, in Southeast Asia, 79 00:04:00,585 --> 00:04:04,829 its legendary temple, Angkor Wat, 80 00:04:04,830 --> 00:04:06,556 is its most iconic structure. 81 00:04:08,420 --> 00:04:12,320 But Angkor Wat is the largest of more than a thousand temples 82 00:04:12,321 --> 00:04:16,463 spread across more than 150 square miles. 83 00:04:19,500 --> 00:04:20,776 A lot of these temples have really 84 00:04:20,777 --> 00:04:21,777 been left to the jungle. 85 00:04:21,778 --> 00:04:23,331 So trees are overgrowing them. 86 00:04:23,332 --> 00:04:24,953 The vegetation is everywhere. 87 00:04:24,954 --> 00:04:26,334 And when you walk into them, 88 00:04:26,335 --> 00:04:28,439 you sometimes feel like you're the first person 89 00:04:28,440 --> 00:04:32,340 that's stepped foot in them for over a thousand years. 90 00:04:32,341 --> 00:04:34,342 The temples themselves have a sense 91 00:04:34,343 --> 00:04:35,791 of mystery to them. 92 00:04:35,792 --> 00:04:36,827 You don't know exactly what happened here 93 00:04:36,828 --> 00:04:39,208 or why they were abandoned. 94 00:04:39,209 --> 00:04:42,936 This land has been home to the Khmer people 95 00:04:42,937 --> 00:04:44,386 for thousands of years, 96 00:04:44,387 --> 00:04:48,148 living in small kingdoms often in conflict with each other, 97 00:04:48,149 --> 00:04:51,220 until the year 802, 98 00:04:51,221 --> 00:04:54,465 when Jayavarman II defeated his rivals 99 00:04:54,466 --> 00:04:59,505 and declared himself a god-king in the Hindu tradition, 100 00:04:59,506 --> 00:05:02,267 and founded the Khmer Empire. 101 00:05:04,200 --> 00:05:06,270 Nearly 100 years later, 102 00:05:06,271 --> 00:05:09,031 the capital of the empire was moved to a new site 103 00:05:09,032 --> 00:05:12,760 on a fertile plain-- the city of Ankgor. 104 00:05:14,762 --> 00:05:16,936 Over the next 500 years, 105 00:05:16,937 --> 00:05:20,388 the empire became the dominant power in Southeast Asia, 106 00:05:20,389 --> 00:05:23,011 ruling over all of what is now Cambodia 107 00:05:23,012 --> 00:05:26,291 and much of Vietnam, Thailand, and Laos. 108 00:05:27,499 --> 00:05:30,156 The kings, who were considered holy, 109 00:05:30,157 --> 00:05:33,055 ruled both political and spiritual life. 110 00:05:33,056 --> 00:05:35,817 Each successive ruler strove to demonstrate his greatness 111 00:05:35,818 --> 00:05:38,544 through major construction projects. 112 00:05:38,545 --> 00:05:40,580 Each new king and each new reign 113 00:05:40,581 --> 00:05:43,203 would try to outbuild the reign before 114 00:05:43,204 --> 00:05:45,483 and build a bigger and more impressive temple. 115 00:05:46,622 --> 00:05:49,520 As Angkor grew, so did the temples, 116 00:05:49,521 --> 00:05:53,041 in number and size, 117 00:05:53,042 --> 00:05:54,905 until the 1300s, 118 00:05:54,906 --> 00:05:57,805 when temple construction abruptly stopped. 119 00:06:00,221 --> 00:06:03,603 Evidence suggests that by the mid-1400s, 120 00:06:03,604 --> 00:06:05,261 Angkor stood empty. 121 00:06:08,644 --> 00:06:11,957 It mysteriously was abandoned. 122 00:06:14,443 --> 00:06:16,651 Well, so the story goes. 123 00:06:16,652 --> 00:06:20,309 And so this place has attracted the fascination 124 00:06:20,310 --> 00:06:22,277 of people from around the world 125 00:06:22,278 --> 00:06:24,486 for many, many hundreds of years. 126 00:06:24,487 --> 00:06:28,732 Partly because the city itself is so prodigiously massive, 127 00:06:28,733 --> 00:06:31,666 and partly because all of this 128 00:06:31,667 --> 00:06:33,668 was apparently left to the jungle 129 00:06:33,669 --> 00:06:35,324 by the Khmer. 130 00:06:35,325 --> 00:06:39,363 The abandonment of Angkor is an enduring mystery. 131 00:06:39,364 --> 00:06:41,434 Who were the people who lived here? 132 00:06:41,435 --> 00:06:43,092 And why did they leave? 133 00:06:44,127 --> 00:06:46,128 The answers are important, 134 00:06:46,129 --> 00:06:49,823 not just for the archaeologists who are excavating here. 135 00:06:52,273 --> 00:06:54,723 Many Cambodians identify as Khmer 136 00:06:54,724 --> 00:06:57,175 and are deeply invested in this ancient place. 137 00:06:58,314 --> 00:07:01,005 Angkor is central to their heritage, 138 00:07:01,006 --> 00:07:04,146 connecting them to their ancestors. 139 00:07:04,147 --> 00:07:06,148 Angkor holds 140 00:07:06,149 --> 00:07:10,014 a profound place in Khmer life. 141 00:07:10,015 --> 00:07:14,641 The very word "Angkor" is deeply rooted in our national identity. 142 00:07:15,745 --> 00:07:19,852 Angkor, we can say, for the Khmer people, it's our soul. 143 00:07:19,853 --> 00:07:21,819 Every one of the Khmer people say that. 144 00:07:21,820 --> 00:07:24,029 "We want to see Angkor before we die." 145 00:07:25,375 --> 00:07:29,275 But the full truth about Angkor and its people has been elusive, 146 00:07:29,276 --> 00:07:30,828 because so much of the city 147 00:07:30,829 --> 00:07:34,074 has long lain hidden beneath the jungle canopy. 148 00:07:36,456 --> 00:07:38,353 We only know of Angkor Wat, 149 00:07:38,354 --> 00:07:40,148 this one-square-kilometer temple, 150 00:07:40,149 --> 00:07:43,531 as being a religious temple, a sacred space. 151 00:07:43,532 --> 00:07:46,672 But were there any people living inside Angkor? 152 00:07:46,673 --> 00:07:47,812 We did not know yet. 153 00:07:48,813 --> 00:07:51,400 We also tried to map the area, 154 00:07:51,401 --> 00:07:54,059 and the vegetation was too thick, was overgrown. 155 00:07:55,302 --> 00:07:57,545 It's incredibly difficult for archaeologists 156 00:07:57,546 --> 00:07:59,961 to map the center of Angkor, where all the large temples are, 157 00:07:59,962 --> 00:08:01,963 because of all the dense vegetation. 158 00:08:01,964 --> 00:08:04,966 But now, with the help of new technology, 159 00:08:04,967 --> 00:08:06,899 archaeologists are trying to see 160 00:08:06,900 --> 00:08:10,143 what has been invisible for centuries. 161 00:08:10,144 --> 00:08:12,283 That's where the lidar data comes in. 162 00:08:12,284 --> 00:08:16,391 Lidar is a powerful laser technology that has recently 163 00:08:16,392 --> 00:08:18,636 become a game changer for archaeologists. 164 00:08:19,878 --> 00:08:21,569 Lidar has been absolutely revolutionary 165 00:08:21,570 --> 00:08:22,777 for our field of archaeology, 166 00:08:22,778 --> 00:08:25,676 because it allows us to see the ground floor 167 00:08:25,677 --> 00:08:28,990 underneath dense vegetation. 168 00:08:28,991 --> 00:08:31,924 We acquire lidar data by putting a drone or a helicopter 169 00:08:31,925 --> 00:08:34,340 or a plane in the air with the lidar device on it. 170 00:08:34,341 --> 00:08:37,136 These devices send out millions of pulses of light. 171 00:08:37,137 --> 00:08:39,034 Most of those pulses bounce off things 172 00:08:39,035 --> 00:08:42,106 that we're not interested in, like buildings or trees, 173 00:08:42,107 --> 00:08:43,487 but some of them, critically, 174 00:08:43,488 --> 00:08:45,454 reach the groundsurface. 175 00:08:45,455 --> 00:08:46,904 What we do is, we measure 176 00:08:46,905 --> 00:08:48,250 the time that it takes 177 00:08:48,251 --> 00:08:49,355 for those groundreturns 178 00:08:49,356 --> 00:08:51,322 to return to the lidar device, 179 00:08:51,323 --> 00:08:54,464 and, using those measurements, calculate distance. 180 00:08:55,500 --> 00:08:57,087 With that information, 181 00:08:57,088 --> 00:08:58,882 we can then strip away all the vegetation 182 00:08:58,883 --> 00:09:02,195 so we can clearly see these archaeological features. 183 00:09:02,196 --> 00:09:04,784 The lidar scans revealed 184 00:09:04,785 --> 00:09:07,167 the breathtaking size of the city. 185 00:09:08,513 --> 00:09:10,203 The data was spectacular. 186 00:09:10,204 --> 00:09:11,273 All of a sudden, we could see 187 00:09:11,274 --> 00:09:13,137 these elements of the urban space 188 00:09:13,138 --> 00:09:15,347 that were completely invisible before. 189 00:09:16,383 --> 00:09:18,902 The lidar data is like the most amazing treasure map, 190 00:09:18,903 --> 00:09:21,111 not because we're looking for gold or statues, 191 00:09:21,112 --> 00:09:24,079 but because it allows us to ask bigger and better questions 192 00:09:24,080 --> 00:09:27,117 about what it was like to live at Angkor. 193 00:09:27,118 --> 00:09:28,359 The amount of detail 194 00:09:28,360 --> 00:09:30,292 that the lidar revealed about the landscape 195 00:09:30,293 --> 00:09:32,122 is absolutely mind-blowing. 196 00:09:32,123 --> 00:09:35,297 We were able to map an additional 20,000 features. 197 00:09:35,298 --> 00:09:39,923 The full scale of the city of Angkor is staggering, 198 00:09:39,924 --> 00:09:43,789 covering more than 150 square miles, 199 00:09:43,790 --> 00:09:45,550 about the size of Denver. 200 00:09:46,655 --> 00:09:48,932 Hundreds of miles of roads 201 00:09:48,933 --> 00:09:51,935 and a complex network of waterways and canals 202 00:09:51,936 --> 00:09:54,075 connected the city. 203 00:09:54,076 --> 00:09:56,491 Hidden in the data were the keys 204 00:09:56,492 --> 00:10:00,633 to knowing how and where the citizens of Angkor lived. 205 00:10:00,634 --> 00:10:03,878 Because Angkor is built on a floodplain, 206 00:10:03,879 --> 00:10:06,156 all of the features were built on mounds. 207 00:10:06,157 --> 00:10:08,020 So when we're looking at the lidar data, 208 00:10:08,021 --> 00:10:10,988 we're not seeing ancient houses themselves, 209 00:10:10,989 --> 00:10:13,923 but we're seeing the mounds these houses were once built on. 210 00:10:14,959 --> 00:10:18,340 This is Angkor Wat, 211 00:10:18,341 --> 00:10:21,378 which is absolutely beautiful in the lidar data. 212 00:10:21,379 --> 00:10:25,140 So these are depressions and elevations in the land 213 00:10:25,141 --> 00:10:27,246 that we can very clearly see in this lidar imagery. 214 00:10:27,247 --> 00:10:30,974 But it's almost impossible to see these features on the ground 215 00:10:30,975 --> 00:10:33,217 because the vegetation is just so dense. 216 00:10:33,218 --> 00:10:36,669 All of these black dots are house ponds, 217 00:10:36,670 --> 00:10:39,327 and beside them are usually house mounds. 218 00:10:39,328 --> 00:10:43,158 Within the Angkor Wat temple enclosure itself, 219 00:10:43,159 --> 00:10:47,162 the lidar revealed more than 200 of these mounds. 220 00:10:47,163 --> 00:10:49,199 Using the lidar maps as a guide, 221 00:10:49,200 --> 00:10:52,340 Piphal Heng set out to investigate these sites 222 00:10:52,341 --> 00:10:53,755 on the ground. 223 00:10:53,756 --> 00:10:56,034 Those mounds are generally habitation site. 224 00:10:57,070 --> 00:11:01,936 When we saw a similar pattern inside the Angkor Wat enclosure, 225 00:11:01,937 --> 00:11:05,077 we started to excavate those mounds. 226 00:11:05,078 --> 00:11:09,081 Turned out that those mound have residential debris: 227 00:11:09,082 --> 00:11:10,392 ceramics, 228 00:11:10,393 --> 00:11:12,429 Angkorian stonewares, 229 00:11:12,430 --> 00:11:14,465 and trade ware from China. 230 00:11:14,466 --> 00:11:16,951 So what we didn't know was, those mound and ponds 231 00:11:16,952 --> 00:11:19,161 were arranged into a grid system. 232 00:11:20,196 --> 00:11:22,198 That's when lidar came around. 233 00:11:25,719 --> 00:11:27,824 So here we are in the eastern section 234 00:11:27,825 --> 00:11:29,618 of the Angkor Wat enclosure. 235 00:11:29,619 --> 00:11:33,105 What I am standing on now, what had been a house mound, 236 00:11:33,106 --> 00:11:35,590 and because of the overgrowth, 237 00:11:35,591 --> 00:11:38,489 we can hardly tell the topography change. 238 00:11:38,490 --> 00:11:40,699 But lidar map allow us to pick up 239 00:11:40,700 --> 00:11:44,357 just a slight topographic change that allow us to identify 240 00:11:44,358 --> 00:11:48,085 whether this area was a mound, a pond to my right. 241 00:11:48,086 --> 00:11:51,675 The lidar data shows that we are standing 242 00:11:51,676 --> 00:11:54,816 in an urban block that is replicated 243 00:11:54,817 --> 00:11:56,438 into other urban blocks 244 00:11:56,439 --> 00:12:00,443 covering the entire Angkor Wat enclosure. 245 00:12:01,479 --> 00:12:03,031 You can tell when you're walking around 246 00:12:03,032 --> 00:12:04,274 that there's mounds there. 247 00:12:04,275 --> 00:12:05,516 It's really forested, 248 00:12:05,517 --> 00:12:08,209 but you can see that the landscape undulates 249 00:12:08,210 --> 00:12:09,797 quite a bit. 250 00:12:09,798 --> 00:12:11,143 Archaeologist Alison Carter 251 00:12:11,144 --> 00:12:13,214 has been collaborating with Piphal 252 00:12:13,215 --> 00:12:15,250 to try to decipher what life was like 253 00:12:15,251 --> 00:12:17,356 at the Angkor Wat complex. 254 00:12:17,357 --> 00:12:21,187 The lidar in Angkor was incredibly eye-opening, 255 00:12:21,188 --> 00:12:24,087 because you just see that they didn't just build Angkor Wat, 256 00:12:24,088 --> 00:12:25,951 which is a spectacular temple, right? 257 00:12:25,952 --> 00:12:28,437 Like, they were transforming the entire landscape. 258 00:12:29,438 --> 00:12:32,854 And transforming it with extreme precision. 259 00:12:32,855 --> 00:12:35,098 If you look at the temple structures 260 00:12:35,099 --> 00:12:38,584 and align them with the gates of Angkor Wat, 261 00:12:38,585 --> 00:12:40,931 you would see that the grid system 262 00:12:40,932 --> 00:12:43,244 was actually aligned with the temple. 263 00:12:43,245 --> 00:12:45,246 It was all an engineered landscape. 264 00:12:45,247 --> 00:12:49,353 The remarkable urban design of the Khmer 265 00:12:49,354 --> 00:12:51,217 extended to the even larger 266 00:12:51,218 --> 00:12:52,599 royal complex, Angkor Thom. 267 00:12:54,808 --> 00:12:56,464 You can see, this is Angkor Wat. 268 00:12:56,465 --> 00:12:58,259 There's a huge moat that's very visible 269 00:12:58,260 --> 00:12:59,329 from the satellite imagery. 270 00:12:59,330 --> 00:13:01,780 And then up here is Angkor Thom. 271 00:13:01,781 --> 00:13:04,127 And you can see the moat of Angkor Thom. 272 00:13:04,128 --> 00:13:07,061 But you really can't see all of that detail 273 00:13:07,062 --> 00:13:10,892 that becomes so clear and obvious in the lidar data. 274 00:13:10,893 --> 00:13:12,514 So you can just imagine, 275 00:13:12,515 --> 00:13:17,796 when you enter Angkor Thom through these magnificent gates, 276 00:13:17,797 --> 00:13:20,799 it would have been a bustling city on either side of you. 277 00:13:20,800 --> 00:13:22,145 Again and again, 278 00:13:22,146 --> 00:13:24,837 the lidar revealed sprawling neighborhoods 279 00:13:24,838 --> 00:13:28,427 around Angkor's more than 1,000 temples. 280 00:13:28,428 --> 00:13:32,396 Combining this with the finds from excavations on the ground 281 00:13:32,397 --> 00:13:34,295 and new technologies, 282 00:13:34,296 --> 00:13:37,505 a team of archaeologists is finally able to crack 283 00:13:37,506 --> 00:13:40,404 one of the city's biggest mysteries: 284 00:13:40,405 --> 00:13:45,547 the size of Angkor's population at its peak around 1250. 285 00:13:45,548 --> 00:13:46,548 To answer that question 286 00:13:46,549 --> 00:13:47,964 of how many people lived at Angkor, 287 00:13:47,965 --> 00:13:49,344 we compiled all of the data 288 00:13:49,345 --> 00:13:51,174 that we had-- C14 dates, 289 00:13:51,175 --> 00:13:53,659 ceramic evidence from excavation, 290 00:13:53,660 --> 00:13:55,626 and we used some new, cutting-edge algorithms 291 00:13:55,627 --> 00:13:57,249 and machine-learning techniques 292 00:13:57,250 --> 00:14:00,494 to try to model the development of the city over time. 293 00:14:01,702 --> 00:14:04,808 I was part of a group of people that were working 294 00:14:04,809 --> 00:14:08,398 on trying to understand the growth of the city of Angkor. 295 00:14:08,399 --> 00:14:10,193 If you compare, this one is better. 296 00:14:10,194 --> 00:14:11,953 That one's better, it's a much bigger piece. 297 00:14:11,954 --> 00:14:13,299 Yeah, so that'll be great to collect 298 00:14:13,300 --> 00:14:14,887 from this mound. 299 00:14:14,888 --> 00:14:16,095 That's a really good example 300 00:14:16,096 --> 00:14:18,477 of how we can bring in good, old-fashioned, 301 00:14:18,478 --> 00:14:19,927 on-the-ground dirt archaeology 302 00:14:19,928 --> 00:14:21,376 with all of these new technologies. 303 00:14:21,377 --> 00:14:23,827 From our excavations, it seems 304 00:14:23,828 --> 00:14:26,140 like there's just one household or family per mound. 305 00:14:26,141 --> 00:14:28,556 We use ethnographic data, then, to estimate 306 00:14:28,557 --> 00:14:31,007 that there's about five people in a family. 307 00:14:31,008 --> 00:14:32,801 Another important piece of data 308 00:14:32,802 --> 00:14:33,975 was from inscriptions. 309 00:14:33,976 --> 00:14:35,943 A lot of the temples have foundation dates. 310 00:14:35,944 --> 00:14:37,910 And that was really important to understand 311 00:14:37,911 --> 00:14:39,808 when they were built. 312 00:14:39,809 --> 00:14:43,502 And inscriptions in two of the larger temples provide 313 00:14:43,503 --> 00:14:45,469 crucial clues about the population, 314 00:14:45,470 --> 00:14:49,749 which are of special interest to archaeologist Andrew Harris. 315 00:14:49,750 --> 00:14:52,961 They actually list the numbers of temple staff. 316 00:14:53,962 --> 00:14:57,343 These include government officials, dancers, laborers, 317 00:14:57,344 --> 00:15:02,383 and also, how many people that the temple staff oversaw 318 00:15:02,384 --> 00:15:04,592 in the surrounding villages, 319 00:15:04,593 --> 00:15:09,045 numbering between 200,000 and 300,000 for both temples. 320 00:15:09,046 --> 00:15:11,668 And then Sarah took that data, the lidar data, 321 00:15:11,669 --> 00:15:13,497 she used some machine-learning algorithms. 322 00:15:13,498 --> 00:15:15,361 We brought this all together 323 00:15:15,362 --> 00:15:17,260 to try and create a model for how Angkor grew. 324 00:15:17,261 --> 00:15:19,710 The final estimate from their calculations 325 00:15:19,711 --> 00:15:21,436 was staggering. 326 00:15:21,437 --> 00:15:23,473 From our estimates, we think, at its height, 327 00:15:23,474 --> 00:15:25,268 that it had about 700,000 to 900,000 people 328 00:15:25,269 --> 00:15:28,029 living in the greater Angkor region. 329 00:15:28,030 --> 00:15:30,169 That would have made it one of the largest, 330 00:15:30,170 --> 00:15:32,965 if not the largest, city in the world at the time. 331 00:15:32,966 --> 00:15:36,072 The discovery of Angkor's true size 332 00:15:36,073 --> 00:15:38,005 was a major breakthrough, 333 00:15:38,006 --> 00:15:39,696 but it was all the more impressive 334 00:15:39,697 --> 00:15:42,009 because of Angkor's location. 335 00:15:42,010 --> 00:15:44,563 Because the entire city was built 336 00:15:44,564 --> 00:15:47,048 on a water-soaked floodplain. 337 00:15:47,049 --> 00:15:48,567 Every year, 338 00:15:48,568 --> 00:15:52,641 the rainy season brings massive rainfall and heavy flooding. 339 00:15:54,505 --> 00:15:57,715 My family's connection with Angkor runs deep. 340 00:15:58,716 --> 00:16:00,130 During my childhood, 341 00:16:00,131 --> 00:16:03,789 my grandparents and my parents frequent 342 00:16:03,790 --> 00:16:05,584 the pagoda in Angkor. 343 00:16:05,585 --> 00:16:08,035 So I've been coming to Angkor since... 344 00:16:08,036 --> 00:16:09,381 Yeah, for forever. 345 00:16:09,382 --> 00:16:11,176 Growing up here provide 346 00:16:11,177 --> 00:16:13,902 a different perspective on the water. 347 00:16:13,903 --> 00:16:17,251 We have the Great Lake to the south. 348 00:16:17,252 --> 00:16:19,701 The lake level change drastically 349 00:16:19,702 --> 00:16:21,289 during the rainy season, 350 00:16:21,290 --> 00:16:24,534 particularly around October and November. 351 00:16:24,535 --> 00:16:26,812 The great Tonlé Sap lake 352 00:16:26,813 --> 00:16:29,677 often quadruples in size in the rainy season, 353 00:16:29,678 --> 00:16:32,576 flooding vast areas of the countryside. 354 00:16:32,577 --> 00:16:34,026 In the dry season, 355 00:16:34,027 --> 00:16:37,340 nearly half the year, almost no rain falls. 356 00:16:37,341 --> 00:16:39,342 Why would the Khmer build in a place 357 00:16:39,343 --> 00:16:42,518 with such extreme swings between flooding and droughts? 358 00:16:44,589 --> 00:16:46,073 Water is incredibly important for the Khmer Empire. 359 00:16:46,074 --> 00:16:48,523 Almost everything revolves around it. 360 00:16:48,524 --> 00:16:51,802 And one of the most important functions was 361 00:16:51,803 --> 00:16:55,116 irrigating the main agricultural crop of the empire: 362 00:16:55,117 --> 00:16:56,669 rice. 363 00:16:56,670 --> 00:16:57,946 The economy of Angkor 364 00:16:57,947 --> 00:17:00,190 was underpinned by rice agriculture, 365 00:17:00,191 --> 00:17:03,573 which is heavily dependent on a stable supply of water. 366 00:17:03,574 --> 00:17:06,645 There's a strong relationship between water, the floodplain, 367 00:17:06,646 --> 00:17:08,509 wet rice agriculture, 368 00:17:08,510 --> 00:17:11,443 and the early phase of Angkor period. 369 00:17:11,444 --> 00:17:14,411 As the Khmer Empire and city expanded, 370 00:17:14,412 --> 00:17:16,655 controlling the flow of water was key 371 00:17:16,656 --> 00:17:18,622 for their economy, trade, 372 00:17:18,623 --> 00:17:21,004 and ability to feed a growing population. 373 00:17:21,005 --> 00:17:23,765 But how did they do it? 374 00:17:23,766 --> 00:17:26,389 Visible remnants suggested there had once been 375 00:17:26,390 --> 00:17:28,047 a complex water system. 376 00:17:29,255 --> 00:17:31,118 But it took lidar to reveal 377 00:17:31,119 --> 00:17:34,121 the full scope of the Khmer engineering. 378 00:17:34,122 --> 00:17:36,502 So, with the lidar, we were able to create this map, 379 00:17:36,503 --> 00:17:38,263 which very clearly shows 380 00:17:38,264 --> 00:17:40,299 the layout of the water management system 381 00:17:40,300 --> 00:17:42,198 and how water flows into the city, 382 00:17:42,199 --> 00:17:43,647 through the city, 383 00:17:43,648 --> 00:17:45,063 and then, how there are exit channels 384 00:17:45,064 --> 00:17:47,548 to remove excess water. 385 00:17:47,549 --> 00:17:50,930 The design was both ambitious and ingenious. 386 00:17:50,931 --> 00:17:53,761 A series of massive reservoirs called barays 387 00:17:53,762 --> 00:17:56,212 collected water in the rainy season. 388 00:17:56,213 --> 00:17:59,249 So here at Angkor, we can see the large barays. 389 00:17:59,250 --> 00:18:00,871 Here's the West and East Baray, 390 00:18:00,872 --> 00:18:02,770 and then all of these straight lines 391 00:18:02,771 --> 00:18:05,152 funneling into the city, 392 00:18:05,153 --> 00:18:07,223 these are manmade water channels. 393 00:18:07,224 --> 00:18:09,535 So this is rerouting water 394 00:18:09,536 --> 00:18:13,781 from northern areas of Cambodia into Angkor. 395 00:18:15,266 --> 00:18:17,957 The water was captured from natural rivers 396 00:18:17,958 --> 00:18:21,409 and moved into storage in these massive reservoirs. 397 00:18:21,410 --> 00:18:23,757 Those barays were really the centerpiece of the whole system. 398 00:18:24,758 --> 00:18:26,552 The largest baray stretched across 399 00:18:26,553 --> 00:18:29,073 more than six square miles. 400 00:18:30,557 --> 00:18:32,213 All of these features are so big 401 00:18:32,214 --> 00:18:34,216 that you can literally see them from space. 402 00:18:36,184 --> 00:18:39,117 That's the beginning of Angkor's power-- 403 00:18:39,118 --> 00:18:40,395 water management. 404 00:18:41,603 --> 00:18:43,742 Those reservoirs are fantastically important. 405 00:18:43,743 --> 00:18:45,364 They hold huge volumes of water, 406 00:18:45,365 --> 00:18:47,194 which can be distributed in the dry season, 407 00:18:47,195 --> 00:18:49,506 if you want a second crop of rice, for example. 408 00:18:49,507 --> 00:18:51,922 So it really kind of super-boosts your productivity 409 00:18:51,923 --> 00:18:54,201 in those parts of Angkor which are downstream 410 00:18:54,202 --> 00:18:55,375 of those reservoirs. 411 00:18:56,687 --> 00:19:00,173 And the system extended far beyond the city itself. 412 00:19:01,416 --> 00:19:02,692 The landscape around Angkor 413 00:19:02,693 --> 00:19:05,419 is actually at a slight incline, about one percent, 414 00:19:05,420 --> 00:19:06,799 so the East and West Barays 415 00:19:06,800 --> 00:19:09,526 can catch water as it comes into the city, hold it, 416 00:19:09,527 --> 00:19:12,668 and then redistribute it through the different channels. 417 00:19:14,532 --> 00:19:17,085 Taming the water was a major feat 418 00:19:17,086 --> 00:19:18,604 of urban engineering, 419 00:19:18,605 --> 00:19:23,334 with hundreds of miles of canals and reservoirs, all dug by hand. 420 00:19:24,611 --> 00:19:27,682 But the floodplain also created a major challenge 421 00:19:27,683 --> 00:19:31,480 for an empire intent on creating monumental architecture. 422 00:19:32,723 --> 00:19:34,379 It's a bit of a difficult spot 423 00:19:34,380 --> 00:19:36,898 for building heavy temples like Angkor. 424 00:19:36,899 --> 00:19:38,279 So in order to do this, 425 00:19:38,280 --> 00:19:41,110 they had some really ingenious engineering strategies. 426 00:19:42,698 --> 00:19:44,734 How did the Khmer manage to build 427 00:19:44,735 --> 00:19:47,599 massive stone structures on soft, deep soil 428 00:19:47,600 --> 00:19:49,842 surrounded by water? 429 00:19:49,843 --> 00:19:52,639 The first clue may be in the choice of building material. 430 00:19:54,814 --> 00:19:58,920 Hang Peou is the head of APSARA, the organization in charge 431 00:19:58,921 --> 00:20:02,270 of restoring the city of Angkor and the surrounding area. 432 00:20:04,064 --> 00:20:05,686 The priority of APSARA, 433 00:20:05,687 --> 00:20:07,446 it's about the conservation, 434 00:20:07,447 --> 00:20:11,382 how we can preserve the temple without falling. 435 00:20:12,832 --> 00:20:15,178 Before we start to make the restoration, 436 00:20:15,179 --> 00:20:17,663 we need to do research. 437 00:20:17,664 --> 00:20:21,598 The highly decorated walls of Angkor's temples are built 438 00:20:21,599 --> 00:20:24,187 of fine-grained sandstone, 439 00:20:24,188 --> 00:20:27,086 well-suited for intricate carvings. 440 00:20:27,087 --> 00:20:30,158 But appearances can be deceiving. 441 00:20:30,159 --> 00:20:32,437 Just under the ornate façade 442 00:20:32,438 --> 00:20:35,406 lies the first secret of Khmer construction. 443 00:20:36,614 --> 00:20:39,133 Hidden within the walls and foundation 444 00:20:39,134 --> 00:20:42,378 are blocks of a rough, porous stone called laterite 445 00:20:42,379 --> 00:20:44,760 that can be even lighter than sandstone. 446 00:20:47,280 --> 00:20:49,626 In term of the weight, 447 00:20:49,627 --> 00:20:51,076 it's less heavy. 448 00:20:51,077 --> 00:20:54,148 The core inside they build in the laterite, 449 00:20:54,149 --> 00:20:55,563 and then they put 450 00:20:55,564 --> 00:20:59,153 the limestone around for decoration. 451 00:20:59,154 --> 00:21:02,605 The whole temple's built in that concept. 452 00:21:04,055 --> 00:21:05,677 Using the lighter laterite 453 00:21:05,678 --> 00:21:08,438 greatly reduced the load on the soft ground. 454 00:21:08,439 --> 00:21:11,684 But the stone temples are still incredibly heavy. 455 00:21:12,650 --> 00:21:15,065 The stone that forms Angkor Wat, 456 00:21:15,066 --> 00:21:17,792 towering over 200 feet high, 457 00:21:17,793 --> 00:21:20,001 weighs millions of tons. 458 00:21:20,002 --> 00:21:23,177 And yet, it has survived the wet terrain 459 00:21:23,178 --> 00:21:25,318 for over 900 years. 460 00:21:26,733 --> 00:21:30,011 There must be more to the engineering. 461 00:21:30,012 --> 00:21:32,083 But what? 462 00:21:33,257 --> 00:21:36,017 Archaeologist Neth Simon leads restoration teams 463 00:21:36,018 --> 00:21:37,743 for APSARA. 464 00:21:37,744 --> 00:21:40,228 Her excavations are focused on understanding 465 00:21:40,229 --> 00:21:44,232 the key elements of ancient Khmer engineering. 466 00:21:44,233 --> 00:21:46,925 As a result of the excavation 467 00:21:46,926 --> 00:21:48,858 to see the condition of the foundation, 468 00:21:48,859 --> 00:21:53,518 I was able to understand the ancient techniques 469 00:21:53,519 --> 00:21:55,830 in building the temple. 470 00:21:55,831 --> 00:21:59,765 We observed that before shaping the temple itself, 471 00:21:59,766 --> 00:22:01,664 the ancient builders began by digging down 472 00:22:01,665 --> 00:22:05,461 to reach the natural soil. 473 00:22:05,462 --> 00:22:08,912 They then began compacting the soil inside. 474 00:22:10,536 --> 00:22:13,986 The next step involved filling the foundation 475 00:22:13,987 --> 00:22:16,403 with fine, pink sand. 476 00:22:16,404 --> 00:22:18,923 This was followed by the laterite foundation. 477 00:22:20,200 --> 00:22:24,134 Above it, they laid the base layer using sandstone. 478 00:22:24,135 --> 00:22:26,861 As any trip to the beach reveals, 479 00:22:26,862 --> 00:22:29,899 dry sand is soft and shifts easily, 480 00:22:29,900 --> 00:22:33,213 while wet sand, closer to the water, holds firm. 481 00:22:34,732 --> 00:22:36,319 Water and sand together 482 00:22:36,320 --> 00:22:38,425 can create a solid base for construction. 483 00:22:38,426 --> 00:22:41,082 This could be one reason 484 00:22:41,083 --> 00:22:43,947 the temples at Angkor were surrounded by moats. 485 00:22:43,948 --> 00:22:45,397 Another thing that we can see 486 00:22:45,398 --> 00:22:48,296 is that all of these temples have water features around them, 487 00:22:48,297 --> 00:22:51,438 so each temple, which is marked in red, 488 00:22:51,439 --> 00:22:53,337 they tend to have moats around them. 489 00:22:54,442 --> 00:22:57,098 They built on the sand layer, 490 00:22:57,099 --> 00:22:59,100 and we understand that the sand layers 491 00:22:59,101 --> 00:23:01,517 need a lot of the humidity 492 00:23:01,518 --> 00:23:03,277 to make it stronger 493 00:23:03,278 --> 00:23:05,866 to support the load of the temple. 494 00:23:05,867 --> 00:23:08,593 The moats were, and still are, 495 00:23:08,594 --> 00:23:11,458 key to maintaining the required level of moisture 496 00:23:11,459 --> 00:23:13,391 beneath the biggest buildings. 497 00:23:13,392 --> 00:23:16,324 The water in the moats provides stability to the sand, 498 00:23:16,325 --> 00:23:17,740 which allows them to hold 499 00:23:17,741 --> 00:23:19,674 the heavy, heavy stone structures up. 500 00:23:22,331 --> 00:23:24,229 These innovations demonstrate 501 00:23:24,230 --> 00:23:27,406 that the Khmer were masters of hydraulic engineering. 502 00:23:28,855 --> 00:23:30,718 As do the hidden features that enabled 503 00:23:30,719 --> 00:23:34,896 Angkor's massive reservoirs, the barays, to function. 504 00:23:36,794 --> 00:23:40,487 Cambodian archaeologist An Sopheap and his team 505 00:23:40,488 --> 00:23:42,627 are excavating a unique location 506 00:23:42,628 --> 00:23:45,457 on the edge of the Eastern Baray, 507 00:23:45,458 --> 00:23:48,806 an ancient reservoir long dry and now covered in jungle. 508 00:23:52,638 --> 00:23:54,984 Right in front of me is the East Baray, 509 00:23:54,985 --> 00:23:58,470 a water reservoir from the Angkor era. 510 00:23:58,471 --> 00:24:01,404 These are the ruins of an ornate stone pier 511 00:24:01,405 --> 00:24:03,026 overlooking the baray. 512 00:24:03,027 --> 00:24:06,858 The Cambodian government hopes to restore the pier 513 00:24:06,859 --> 00:24:08,998 and partially repair the reservoir 514 00:24:08,999 --> 00:24:11,518 to make it functional once more. 515 00:24:11,519 --> 00:24:15,177 The first step is to understand how both were constructed. 516 00:24:17,939 --> 00:24:21,320 But while excavating the pier and the reservoir wall, 517 00:24:21,321 --> 00:24:24,910 they found an unexpected surprise. 518 00:24:24,911 --> 00:24:28,673 At the excavation site I opened here, 519 00:24:28,674 --> 00:24:31,710 we found the foundation of the pier, 520 00:24:31,711 --> 00:24:33,230 made from laterite rock. 521 00:24:34,265 --> 00:24:36,474 Hidden beneath the wall of the baray 522 00:24:36,475 --> 00:24:39,304 is a laterite stone foundation 523 00:24:39,305 --> 00:24:42,859 extending more than 50 feet out into the reservoir. 524 00:24:45,000 --> 00:24:48,555 This work is important because it reveals a new discovery. 525 00:24:48,556 --> 00:24:51,143 We had never seen a construction 526 00:24:51,144 --> 00:24:53,870 with laterite sloping like this before. 527 00:24:53,871 --> 00:24:57,598 The next step is to determine if this massive foundation 528 00:24:57,599 --> 00:25:01,084 extends along the banks of the reservoir, 529 00:25:01,085 --> 00:25:02,672 beyond the area of the pier. 530 00:25:04,813 --> 00:25:08,609 We opened another excavation site ten meters to the south 531 00:25:08,610 --> 00:25:11,923 and saw the structure continues with four more steps. 532 00:25:11,924 --> 00:25:14,581 But we only exposed a small section 533 00:25:14,582 --> 00:25:15,927 to confirm. 534 00:25:15,928 --> 00:25:18,205 In the future, we'll keep excavating 535 00:25:18,206 --> 00:25:20,587 to see if the laterite structure 536 00:25:20,588 --> 00:25:22,624 surrounds the water reservoir or ends somewhere. 537 00:25:24,592 --> 00:25:28,111 No one knows yet how far this stone foundation extends 538 00:25:28,112 --> 00:25:29,941 around the baray. 539 00:25:29,942 --> 00:25:32,460 If this structure 540 00:25:32,461 --> 00:25:33,945 goes around the reservoir or part of it, 541 00:25:33,946 --> 00:25:38,156 it would be a new discovery for the Angkor area. 542 00:25:38,157 --> 00:25:39,606 The pier itself 543 00:25:39,607 --> 00:25:43,576 was a very special structure for Angkor's Hindu god-kings. 544 00:25:46,268 --> 00:25:48,166 This pier was used by the king 545 00:25:48,167 --> 00:25:51,479 to offer alms at the temple located at the center 546 00:25:51,480 --> 00:25:53,206 of the eastern reservoir. 547 00:25:54,829 --> 00:25:58,210 In the middle of each reservoir was an island temple. 548 00:25:58,211 --> 00:26:00,040 The barays were more than just 549 00:26:00,041 --> 00:26:01,939 a brilliant piece of hydraulic engineering. 550 00:26:02,975 --> 00:26:04,665 Here's the East Baray. 551 00:26:04,666 --> 00:26:06,529 And you can clearly see both in the mapping 552 00:26:06,530 --> 00:26:07,806 and in the lidar data 553 00:26:07,807 --> 00:26:09,808 that there's a huge temple in the middle of it. 554 00:26:09,809 --> 00:26:14,917 These large reservoirs were both functional and spiritual. 555 00:26:14,918 --> 00:26:16,608 The kings of the Khmer Empire played both 556 00:26:16,609 --> 00:26:18,403 a political and a religious role. 557 00:26:18,404 --> 00:26:20,543 In addition to being head of the army, 558 00:26:20,544 --> 00:26:22,407 the king was also a king-god, 559 00:26:22,408 --> 00:26:25,168 so head of the religious system, as well. 560 00:26:25,169 --> 00:26:28,516 Every king left an imprint of himself 561 00:26:28,517 --> 00:26:30,588 if he was powerful enough 562 00:26:30,589 --> 00:26:32,141 to create a mark on the landscape. 563 00:26:32,142 --> 00:26:34,246 Dozens of temples here 564 00:26:34,247 --> 00:26:38,043 are reflective of the absolute power over nature, 565 00:26:38,044 --> 00:26:41,046 over people, and over the landscape 566 00:26:41,047 --> 00:26:44,533 that they manifested during their reign. 567 00:26:46,432 --> 00:26:47,674 Over the centuries, 568 00:26:47,675 --> 00:26:49,676 rulers built larger and larger temples 569 00:26:49,677 --> 00:26:52,230 as the Khmer Empire expanded. 570 00:26:52,231 --> 00:26:54,853 Early in his reign, in the 1100s, 571 00:26:54,854 --> 00:26:58,616 King Suryavarman II outdid all of his predecessors, 572 00:26:58,617 --> 00:27:00,549 building Angkor Wat. 573 00:27:01,965 --> 00:27:04,483 Angkor Wat was a huge project. 574 00:27:04,484 --> 00:27:06,762 It would involve so many workers and so many craftsmen 575 00:27:06,763 --> 00:27:08,073 to be able to build it. 576 00:27:08,074 --> 00:27:11,318 Dedicated to the Hindu god Vishnu, 577 00:27:11,319 --> 00:27:16,392 nearly every surface of Angkor Wat was highly decorated. 578 00:27:16,393 --> 00:27:19,050 Traces of paint found on the carved walls and ceilings 579 00:27:19,051 --> 00:27:21,155 hint at its ornate history. 580 00:27:21,156 --> 00:27:23,295 All of the reliefs on the temples 581 00:27:23,296 --> 00:27:25,815 were originally painted in vibrant colors. 582 00:27:25,816 --> 00:27:30,371 Immense carved panels with scenes from Hindu texts 583 00:27:30,372 --> 00:27:32,753 run down vast hallways. 584 00:27:32,754 --> 00:27:37,655 Thousands of priests, dancers, and attendants 585 00:27:37,656 --> 00:27:40,623 filled the temple and its grounds. 586 00:27:40,624 --> 00:27:44,834 It was a ceremonial center on a grand scale, 587 00:27:44,835 --> 00:27:48,113 demonstrating the glory of Vishnu 588 00:27:48,114 --> 00:27:50,633 and the power of the king. 589 00:27:50,634 --> 00:27:52,428 Temples were not just places of worship. 590 00:27:52,429 --> 00:27:54,775 The kings were also using them 591 00:27:54,776 --> 00:27:56,501 to demonstrate their power. 592 00:27:56,502 --> 00:27:58,779 So they probably were really acting 593 00:27:58,780 --> 00:28:01,230 as this kind of billboard for the king and the king's power 594 00:28:01,231 --> 00:28:03,094 and putting his stamp on the landscape. 595 00:28:03,095 --> 00:28:06,994 Wealthy and prosperous, the Khmer Empire 596 00:28:06,995 --> 00:28:10,895 was an attractive target for neighboring powers. 597 00:28:10,896 --> 00:28:14,208 Carved scenes at Angkor illustrate the story 598 00:28:14,209 --> 00:28:16,660 of one major conflict. 599 00:28:18,041 --> 00:28:21,975 In 1177, the nearby kingdom of Cham 600 00:28:21,976 --> 00:28:25,841 invaded Angkor in a surprise attack. 601 00:28:25,842 --> 00:28:29,292 To reclaim the city and restore power to the empire 602 00:28:29,293 --> 00:28:33,055 would take one of the strongest of the Khmer kings, 603 00:28:33,056 --> 00:28:34,540 Jayavarman VII. 604 00:28:36,300 --> 00:28:39,026 In the year 1177, the Chams conquered Angkor 605 00:28:39,027 --> 00:28:40,166 and occupied Angkor. 606 00:28:41,720 --> 00:28:45,930 Jayavarman VII made it his vow to reconquer Angkor. 607 00:28:45,931 --> 00:28:48,933 And part of this is depicted 608 00:28:48,934 --> 00:28:50,797 through various campaigns of warfare. 609 00:28:50,798 --> 00:28:53,385 This is probably the most elaborate of those campaigns, 610 00:28:53,386 --> 00:28:55,180 and it involves a naval battle. 611 00:28:55,181 --> 00:28:59,598 What we can tell here is that one, it was intensive. 612 00:28:59,599 --> 00:29:00,979 It was violent. 613 00:29:00,980 --> 00:29:02,981 You could see the people falling overboard. 614 00:29:02,982 --> 00:29:05,777 Most of them have been stabbed or dead or whatnot. 615 00:29:05,778 --> 00:29:07,227 And a lovely crocodile 616 00:29:07,228 --> 00:29:11,093 eating a poor Cham who's fallen overboard. 617 00:29:11,094 --> 00:29:12,853 So, through a series of campaigns 618 00:29:12,854 --> 00:29:14,613 lasting several years, 619 00:29:14,614 --> 00:29:17,064 he was able to eventually vanquish the Chams. 620 00:29:19,274 --> 00:29:22,414 With the enemy defeated and the Khmer back in power, 621 00:29:22,415 --> 00:29:27,592 Jayavarman VII would usher in Angkor's golden age. 622 00:29:27,593 --> 00:29:29,697 During his reign, he gave back to the public in many ways. 623 00:29:29,698 --> 00:29:31,113 He constructed hospitals 624 00:29:31,114 --> 00:29:32,839 and he built a number of different temples. 625 00:29:32,840 --> 00:29:35,117 This is a scene of a hospital. 626 00:29:35,118 --> 00:29:39,293 Here you have women giving birth, making medicine. 627 00:29:39,294 --> 00:29:43,332 This was a major point during the reign of Jayavarman VII. 628 00:29:43,333 --> 00:29:46,887 He built, I believe, 102 hospitals 629 00:29:46,888 --> 00:29:49,441 across the Angkorian empire. 630 00:29:49,442 --> 00:29:52,306 Alongside his support of public health, 631 00:29:52,307 --> 00:29:53,998 Jayavarman carried on the tradition 632 00:29:53,999 --> 00:29:56,448 of his Khmer predecessors-- 633 00:29:56,449 --> 00:29:58,588 monumental construction. 634 00:29:58,589 --> 00:30:00,038 When kings came into power, 635 00:30:00,039 --> 00:30:02,903 they all had specific mandates that they had to accomplish. 636 00:30:02,904 --> 00:30:05,181 And a lot of this revolved around temple building. 637 00:30:05,182 --> 00:30:09,841 Angkorian kings had a undocumented habit 638 00:30:09,842 --> 00:30:12,361 of trying to one-up their predecessors. 639 00:30:12,362 --> 00:30:14,259 If you think about Suryavarman II, 640 00:30:14,260 --> 00:30:17,642 he built the world's largest religious monument, Angkor Wat. 641 00:30:17,643 --> 00:30:21,542 Jayavarman VII left the largest architectural footprint 642 00:30:21,543 --> 00:30:23,441 on the Angkorian landscape 643 00:30:23,442 --> 00:30:25,995 of any monarch in Cambodian history. 644 00:30:25,996 --> 00:30:28,860 The pinnacle of his reign was the construction 645 00:30:28,861 --> 00:30:32,036 of Angkor Thom, an enormous complex 646 00:30:32,037 --> 00:30:36,040 more than five times the size of Angkor Wat. 647 00:30:36,041 --> 00:30:38,801 It is surrounded by eight miles of moat, 648 00:30:38,802 --> 00:30:41,700 and at its center stands a temple different 649 00:30:41,701 --> 00:30:45,704 from any built before or after-- 650 00:30:45,705 --> 00:30:47,052 the Bayon. 651 00:30:48,225 --> 00:30:51,158 The Bayon is not a Hindu temple-- 652 00:30:51,159 --> 00:30:54,368 Jayavarman was a Buddhist. 653 00:30:54,369 --> 00:30:55,922 All of the elite temples 654 00:30:55,923 --> 00:30:57,924 up until the reign of Jayavarman VII 655 00:30:57,925 --> 00:31:01,134 were considered to be Hindu temples of various deities. 656 00:31:01,135 --> 00:31:02,618 One of the most interesting things 657 00:31:02,619 --> 00:31:05,172 about King Jayavarman VII 658 00:31:05,173 --> 00:31:06,794 is that he switched the state religion 659 00:31:06,795 --> 00:31:08,624 from Hinduism to Buddhism. 660 00:31:08,625 --> 00:31:12,110 Hindu worship involves a pantheon of gods 661 00:31:12,111 --> 00:31:14,112 and observation of rituals set out 662 00:31:14,113 --> 00:31:16,666 in the Vedic scriptures, 663 00:31:16,667 --> 00:31:18,461 while Buddhism focuses on enlightenment 664 00:31:18,462 --> 00:31:20,912 through the teachings of the Buddha. 665 00:31:20,913 --> 00:31:27,022 The Bayon temple towers feature 216 enigmatic faces 666 00:31:27,023 --> 00:31:29,748 that may contain a hidden secret. 667 00:31:29,749 --> 00:31:31,543 The faces on the Bayon and the gate 668 00:31:31,544 --> 00:31:33,925 are potentially a Buddhist saint 669 00:31:33,926 --> 00:31:35,996 or they're the king himself. 670 00:31:35,997 --> 00:31:38,930 And the reason we think it's Jayavarman VII himself 671 00:31:38,931 --> 00:31:43,003 is because a number of the images that we know 672 00:31:43,004 --> 00:31:44,522 of Jayavarman VII 673 00:31:44,523 --> 00:31:45,799 look almost identical 674 00:31:45,800 --> 00:31:48,284 to the face towers on the Bayon and on the gates. 675 00:31:48,285 --> 00:31:51,667 Following the reign of Jayavarman VII, 676 00:31:51,668 --> 00:31:53,496 ending around 1218, 677 00:31:53,497 --> 00:31:56,603 Angkor was at the height of its size and influence. 678 00:31:56,604 --> 00:31:59,951 What was life in Angkor like at its peak? 679 00:31:59,952 --> 00:32:02,678 Few written descriptions have survived from the Khmer, 680 00:32:02,679 --> 00:32:04,714 but historians have one detailed account. 681 00:32:04,715 --> 00:32:08,649 In the 13th century, the emperor of China 682 00:32:08,650 --> 00:32:11,480 sent an emissary to Angkor. 683 00:32:11,481 --> 00:32:13,447 Zhou Daguan was ambassador 684 00:32:13,448 --> 00:32:17,520 of Mongolian-controlled China to Cambodia. 685 00:32:17,521 --> 00:32:19,764 He lived in Angkor sometimes 686 00:32:19,765 --> 00:32:22,767 between 1296 and 1297, almost one year. 687 00:32:22,768 --> 00:32:25,287 Zhou Daguan left us a journal, 688 00:32:25,288 --> 00:32:27,737 and it's incredibly valuable in terms of 689 00:32:27,738 --> 00:32:29,532 the types of details that he wrote about. 690 00:32:29,533 --> 00:32:30,913 I'm not sure if heintended 691 00:32:30,914 --> 00:32:32,328 for archaeologists to read this, 692 00:32:32,329 --> 00:32:34,572 but it sure provides a lot of information. 693 00:32:34,573 --> 00:32:39,542 Around the outside of the city walls, there is a large moat. 694 00:32:39,543 --> 00:32:41,337 The walls of the bridges are made of stone 695 00:32:41,338 --> 00:32:44,513 and carved into the shape of snakes. 696 00:32:44,514 --> 00:32:47,343 As an archaeologist, I refer to Zhou Daguan constantly. 697 00:32:47,344 --> 00:32:51,140 He talks about how poor people lived in smaller houses, 698 00:32:51,141 --> 00:32:52,900 and their roofs were made out of thatch, 699 00:32:52,901 --> 00:32:54,661 but richer people would have bigger houses 700 00:32:54,662 --> 00:32:58,044 and their roofs would be made with ceramic roof tiles. 701 00:32:58,045 --> 00:33:03,428 Zhou Daguan's journal described scenes of everyday life. 702 00:33:03,429 --> 00:33:06,569 Their litters are made of pieces of wood 703 00:33:06,570 --> 00:33:08,019 that bend in the middle. 704 00:33:08,020 --> 00:33:11,229 A person sits in the cloth and is carried by two people, 705 00:33:11,230 --> 00:33:12,990 one at each end. 706 00:33:12,991 --> 00:33:17,960 The parasols are made of a strong, thin, red Chinese silk. 707 00:33:17,961 --> 00:33:22,965 But how reliable are Zhou Daguan's descriptions? 708 00:33:22,966 --> 00:33:26,624 His descriptions of daily life are actually backed up 709 00:33:26,625 --> 00:33:30,318 by a lot of what we see on the walls of the Bayon temple. 710 00:33:32,079 --> 00:33:36,013 Zhou Daguan describes Angkor as a bartering system, 711 00:33:36,014 --> 00:33:37,428 and he describes a market day. 712 00:33:37,429 --> 00:33:41,087 He describes how merchants, mostly women, 713 00:33:41,088 --> 00:33:45,161 would lay down their blankets and sell their wares. 714 00:33:46,679 --> 00:33:50,027 The local people who know how to trade are all women. 715 00:33:50,028 --> 00:33:53,064 Small market transactions are paid for in rice 716 00:33:53,065 --> 00:33:56,378 or other grain and Chinese goods. 717 00:33:56,379 --> 00:34:00,209 Larger in size are paid with cloth. 718 00:34:00,210 --> 00:34:03,592 There's these bas-reliefs of people cooking and eating food, 719 00:34:03,593 --> 00:34:04,834 and then, in our archaeological excavations, 720 00:34:04,835 --> 00:34:07,872 we find really similar materials. 721 00:34:07,873 --> 00:34:11,462 When we are excavating an, an occupation area, 722 00:34:11,463 --> 00:34:12,463 and you're, like, "Oh, this looks 723 00:34:12,464 --> 00:34:13,602 just like what's on the Bayon," 724 00:34:13,603 --> 00:34:15,086 like, you can really see 725 00:34:15,087 --> 00:34:17,192 how these different sources of evidence come together 726 00:34:17,193 --> 00:34:20,160 to give you a more complete picture of the past. 727 00:34:20,161 --> 00:34:21,196 That record represents 728 00:34:21,197 --> 00:34:22,369 a fantastic contribution 729 00:34:22,370 --> 00:34:23,922 to our understanding of the life of the city. 730 00:34:23,923 --> 00:34:25,131 And at that time, 731 00:34:25,132 --> 00:34:26,994 the king and the court were very impressive, 732 00:34:26,995 --> 00:34:28,755 the city was enormous, 733 00:34:28,756 --> 00:34:31,137 and there was clearly a lot of wealth floating around. 734 00:34:31,138 --> 00:34:34,312 Above the gates are stone Buddha heads. 735 00:34:34,313 --> 00:34:37,212 One of them is decorated with gold. 736 00:34:37,213 --> 00:34:41,630 In the center of the capital is a gold tower. 737 00:34:41,631 --> 00:34:43,149 Zhou Daguan describes Angkor 738 00:34:43,150 --> 00:34:46,669 as a very active, very vibrant metropolis. 739 00:34:46,670 --> 00:34:48,499 He talks about the significant amount of wealth 740 00:34:48,500 --> 00:34:50,156 coming out of the palace. 741 00:34:50,157 --> 00:34:52,848 So, Zhou Daguan described 742 00:34:52,849 --> 00:34:54,919 the temples at Angkor 743 00:34:54,920 --> 00:34:58,957 not as these stone mounds that they are today, 744 00:34:58,958 --> 00:35:02,168 but covered in gold and very clearly upkept. 745 00:35:02,169 --> 00:35:06,310 But that upkeep would not last much longer. 746 00:35:06,311 --> 00:35:08,346 Zhou Daguan's record represents 747 00:35:08,347 --> 00:35:09,796 the very kind of last gasp of Angkor 748 00:35:09,797 --> 00:35:15,388 as a spectacular, opulent, thriving metropolis. 749 00:35:15,389 --> 00:35:16,389 From that point forward, 750 00:35:16,390 --> 00:35:18,218 things change dramatically. 751 00:35:25,744 --> 00:35:26,951 This inscription indicates 752 00:35:26,952 --> 00:35:30,713 that this temple was the very last Hindu temple 753 00:35:30,714 --> 00:35:32,819 that was dedicated at Angkor. 754 00:35:32,820 --> 00:35:35,132 We actually have an exact date for it. 755 00:35:35,133 --> 00:35:39,619 It's the 28th of April, 1295 C.E. 756 00:35:39,620 --> 00:35:41,967 Which was just a year before Zhou Daguan showed up. 757 00:35:43,348 --> 00:35:46,109 As far as we know, there are no temples after this one. 758 00:35:50,941 --> 00:35:54,081 As the 1300s continue, Angkor starts to decline. 759 00:35:54,082 --> 00:35:57,084 We start to see evidence from different sources 760 00:35:57,085 --> 00:35:58,603 that population starts to slide. 761 00:35:58,604 --> 00:36:00,537 There are no more inscriptions created, no more temples built. 762 00:36:02,160 --> 00:36:04,575 Official written histories of the Khmer 763 00:36:04,576 --> 00:36:07,509 did not appear again until much later. 764 00:36:07,510 --> 00:36:09,959 There's a bit of a black hole in the historical records 765 00:36:09,960 --> 00:36:14,032 from about the 13th century to the 15th century. 766 00:36:14,033 --> 00:36:16,690 So, it's a big gap-- it's many hundreds of years. 767 00:36:16,691 --> 00:36:21,108 What happened to bring an end to centuries of prosperity 768 00:36:21,109 --> 00:36:23,110 and monumental construction? 769 00:36:23,111 --> 00:36:25,630 No big city like this one is ever going to have 770 00:36:25,631 --> 00:36:28,115 a single reason for its start or its end. 771 00:36:28,116 --> 00:36:31,188 So, in that context and in the complexity of that story, 772 00:36:31,189 --> 00:36:32,603 we can start to accept 773 00:36:32,604 --> 00:36:35,261 that there's no linear, simple, single explanation 774 00:36:35,262 --> 00:36:36,848 for the demise of a place like this, 775 00:36:36,849 --> 00:36:39,265 but, rather, a tangle of different explanations 776 00:36:39,266 --> 00:36:41,439 that happen to coalesce at a particular point. 777 00:36:41,440 --> 00:36:45,132 The warm and humid environment of the Cambodian jungle 778 00:36:45,133 --> 00:36:47,721 works against the archaeologists trying to shed light 779 00:36:47,722 --> 00:36:50,793 on the declining years of Angkor. 780 00:36:50,794 --> 00:36:52,657 The rainforest does not help, 781 00:36:52,658 --> 00:36:55,867 because almost every wooden remain-- 782 00:36:55,868 --> 00:36:58,180 and the vast majority of structures at Angkor 783 00:36:58,181 --> 00:36:59,630 were built in wood-- 784 00:36:59,631 --> 00:37:02,220 deteriorate very, very quickly. 785 00:37:03,359 --> 00:37:06,637 One of the most puzzling aspects of Angkor today 786 00:37:06,638 --> 00:37:10,123 is the complete absence of human remains-- 787 00:37:10,124 --> 00:37:13,091 no bodies, no burials. 788 00:37:13,092 --> 00:37:14,886 This is a very fascinating thing 789 00:37:14,887 --> 00:37:17,717 that's baffled archaeologists for a long time. 790 00:37:17,718 --> 00:37:21,168 There are no funerary remains until much later. 791 00:37:21,169 --> 00:37:24,862 So, for 600 years, one million people, 792 00:37:24,863 --> 00:37:28,693 not a bone, not a cremated remain, 793 00:37:28,694 --> 00:37:31,696 not a funerary jar, 794 00:37:31,697 --> 00:37:33,492 not a trace of a funerary remain. 795 00:37:35,977 --> 00:37:39,704 The lack of bodies, human remains, 796 00:37:39,705 --> 00:37:41,741 in Angkor's archaeological record 797 00:37:41,742 --> 00:37:45,193 is fascinating and frustrating in many ways. 798 00:37:46,194 --> 00:37:47,505 It's very rare for a city 799 00:37:47,506 --> 00:37:50,059 which had 700,000, a million people in it, 800 00:37:50,060 --> 00:37:52,476 that there are so few bodies. 801 00:37:52,477 --> 00:37:55,858 What happened to the bodies of the ancient Khmer? 802 00:37:55,859 --> 00:37:57,343 Well, Zhou Daguan, he talks 803 00:37:57,344 --> 00:37:58,999 about different burial practices. 804 00:37:59,000 --> 00:38:03,590 The body is taken to a remote, uninhabited spot, 805 00:38:03,591 --> 00:38:06,800 where it is thrown down and left. 806 00:38:06,801 --> 00:38:11,840 After that, the vultures, crows, and dogs come and eat it. 807 00:38:13,394 --> 00:38:16,741 But the archaeologists at Angkor are struggling to find 808 00:38:16,742 --> 00:38:19,192 the location of the "sky burials" 809 00:38:19,193 --> 00:38:20,780 that Zhou Daguan described, 810 00:38:20,781 --> 00:38:22,852 where the dead are left to the elements and animals. 811 00:38:23,991 --> 00:38:28,132 He said that they carry the dead outside of the Angkor Thom gates 812 00:38:28,133 --> 00:38:29,892 and then left it outside the wall. 813 00:38:29,893 --> 00:38:31,929 But when we look at lidar data outside the wall, 814 00:38:31,930 --> 00:38:34,725 would have been just settlements everywhere. 815 00:38:34,726 --> 00:38:36,451 Where was that outside the wall? 816 00:38:38,868 --> 00:38:42,491 Burials do tell us a lot about health and the individuals. 817 00:38:42,492 --> 00:38:46,495 So, to find a graveyard, or even to find cremated burials, 818 00:38:46,496 --> 00:38:49,636 that would be phenomenal for Angkorian archaeology. 819 00:38:49,637 --> 00:38:53,986 But so far, we have not found evidence of a burial ground yet. 820 00:38:57,611 --> 00:38:58,990 Without the bodies themselves, 821 00:38:58,991 --> 00:39:02,477 archaeologists are searching for other clues, 822 00:39:02,478 --> 00:39:05,826 hoping to find out, when did everyone leave? 823 00:39:07,862 --> 00:39:11,451 Dan Penny is focusing on the barays and canals, 824 00:39:11,452 --> 00:39:14,627 and the sediments below the surface. 825 00:39:14,628 --> 00:39:16,007 The sediment is accumulating 826 00:39:16,008 --> 00:39:18,872 at the bottom of these reservoirs, ponds, and so on. 827 00:39:18,873 --> 00:39:21,875 They end up as beautiful little traps for material 828 00:39:21,876 --> 00:39:23,014 landing on the surface 829 00:39:23,015 --> 00:39:24,464 and then settling onto the sediment, 830 00:39:24,465 --> 00:39:29,538 and then being buried by subsequent layers of material. 831 00:39:29,539 --> 00:39:30,988 And so it goes, layer upon layer. 832 00:39:30,989 --> 00:39:32,196 We can come along, 833 00:39:32,197 --> 00:39:34,888 hundreds or even thousands of years later, 834 00:39:34,889 --> 00:39:37,753 and take these samples and find this undisturbed material 835 00:39:37,754 --> 00:39:39,548 which faithfully records the conditions 836 00:39:39,549 --> 00:39:42,482 that were occurring when they were deposited. 837 00:39:42,483 --> 00:39:45,209 The moats of Angkor Thom are a fantastic archive. 838 00:39:45,210 --> 00:39:46,900 They've been largely left alone. 839 00:39:46,901 --> 00:39:51,734 So, we can use them as natural archives of change through time. 840 00:39:55,013 --> 00:39:59,154 This core goes all the way back to pre-Angkor. 841 00:39:59,155 --> 00:40:03,020 So, it goes into the alluvial soil beneath the moat, 842 00:40:03,021 --> 00:40:04,918 and we get the whole sequence all the way 843 00:40:04,919 --> 00:40:08,439 through the rise and fall of Angkor and into the modern day. 844 00:40:08,440 --> 00:40:09,647 After processing, 845 00:40:09,648 --> 00:40:13,030 Dan studies the samples from the sediment layers 846 00:40:13,031 --> 00:40:16,136 under a powerful microscope. 847 00:40:16,137 --> 00:40:19,830 So this guy here is a pollen grain from a lotus. 848 00:40:19,831 --> 00:40:21,003 This one is a sedge, 849 00:40:21,004 --> 00:40:22,798 so it's another aquatic plant. 850 00:40:22,799 --> 00:40:24,386 This is a huge chunk of charcoal, 851 00:40:24,387 --> 00:40:26,457 coming out of maybe a domestic fire, 852 00:40:26,458 --> 00:40:27,872 someone's fireplace, where they're cooking. 853 00:40:27,873 --> 00:40:29,287 Could be any source, 854 00:40:29,288 --> 00:40:31,220 but it's invariably associated with people. 855 00:40:31,221 --> 00:40:35,984 Radiocarbon dating adds another layer of information. 856 00:40:35,985 --> 00:40:37,503 Most of the work that I do with radiocarbon 857 00:40:37,504 --> 00:40:39,677 is actually based on dating the pollen grains themselves. 858 00:40:39,678 --> 00:40:41,058 Each of these pollen grains 859 00:40:41,059 --> 00:40:45,856 is about ten to 20 micrometers in diameter. 860 00:40:45,857 --> 00:40:48,962 A micrometer is a thousandth of a millimeter. 861 00:40:48,963 --> 00:40:50,688 So, they're pretty small. 862 00:40:50,689 --> 00:40:53,553 The types of pollen grains-- 863 00:40:53,554 --> 00:40:55,521 found at different depths in the core-- 864 00:40:55,522 --> 00:40:57,902 can reveal when the ancient moats were well maintained 865 00:40:57,903 --> 00:41:00,629 or filled with weeds. 866 00:41:00,630 --> 00:41:02,838 When moats are being maintained, you'll often see species 867 00:41:02,839 --> 00:41:05,496 rooted into the sediment at the bottom of the moat, 868 00:41:05,497 --> 00:41:07,740 as opposed to an unmaintained moat, 869 00:41:07,741 --> 00:41:09,811 which is kind of completely covered 870 00:41:09,812 --> 00:41:12,434 by ferns and grasses and other things. 871 00:41:12,435 --> 00:41:13,573 Once management stops, 872 00:41:13,574 --> 00:41:16,611 the moats will quickly cover with vegetation. 873 00:41:16,612 --> 00:41:19,545 We definitely find evidence of the water systems 874 00:41:19,546 --> 00:41:21,270 not being maintained. 875 00:41:21,271 --> 00:41:24,550 Once they're abandoned, they are permanently abandoned. 876 00:41:24,551 --> 00:41:26,966 And so that represents a very clear horizon for us to, to say, 877 00:41:26,967 --> 00:41:29,140 "Hey, at this point, this water feature 878 00:41:29,141 --> 00:41:30,590 is no longer being managed." 879 00:41:30,591 --> 00:41:32,972 What we are finding increasingly 880 00:41:32,973 --> 00:41:34,491 from a range of different variables, 881 00:41:34,492 --> 00:41:35,940 charcoal among them, 882 00:41:35,941 --> 00:41:37,804 pointing to a progressive decrease 883 00:41:37,805 --> 00:41:39,737 in the intensity of occupation 884 00:41:39,738 --> 00:41:42,084 in the very epicenter of Angkor as a city. 885 00:41:42,085 --> 00:41:44,570 All of these things are decreasing progressively 886 00:41:44,571 --> 00:41:46,813 through the 1300s. 887 00:41:46,814 --> 00:41:51,266 What could have happened at Angkor in the mid-1300s 888 00:41:51,267 --> 00:41:54,407 that would have caused the Khmer to leave? 889 00:41:54,408 --> 00:41:56,823 And the reality is that we don't really know what happened. 890 00:41:56,824 --> 00:41:58,549 There are a number of different hypotheses, 891 00:41:58,550 --> 00:42:01,103 and probably it was a combination of all of them. 892 00:42:01,104 --> 00:42:03,623 So, we need to cast our mind to what other reasons 893 00:42:03,624 --> 00:42:06,592 might there have been for people to start leaving Angkor. 894 00:42:06,593 --> 00:42:09,249 There's another story there sitting underneath, 895 00:42:09,250 --> 00:42:11,113 which is far more interesting and far more important. 896 00:42:11,114 --> 00:42:15,083 Angkor was not the only place to suffer 897 00:42:15,084 --> 00:42:19,121 a major population decrease during the 1300s. 898 00:42:19,122 --> 00:42:22,539 The bubonic plague-- also known as the Black Death-- 899 00:42:22,540 --> 00:42:24,471 that killed millions in Europe 900 00:42:24,472 --> 00:42:27,716 came out of Asia during this century. 901 00:42:27,717 --> 00:42:29,787 The timing fits the abandonment of Angkor, 902 00:42:29,788 --> 00:42:33,102 but is there any evidence of a connection? 903 00:42:35,035 --> 00:42:39,832 Evidence of a pandemic at Angkor would be revolutionary. 904 00:42:39,833 --> 00:42:41,212 The effect of a pandemic 905 00:42:41,213 --> 00:42:43,214 in a pre-industrial city like this one, 906 00:42:43,215 --> 00:42:45,320 which was massive and had a huge population, 907 00:42:45,321 --> 00:42:47,253 would have been catastrophic 908 00:42:47,254 --> 00:42:50,877 and it would likely have led to very rapid depopulation, 909 00:42:50,878 --> 00:42:54,536 particularly by those people that can move. 910 00:42:54,537 --> 00:42:57,056 If there's evidence of a pandemic. 911 00:42:57,057 --> 00:42:59,506 I can assure you there will not be. 912 00:42:59,507 --> 00:43:01,854 Because if you, if you have a pandemic here, 913 00:43:01,855 --> 00:43:05,098 you will find bodies. 914 00:43:05,099 --> 00:43:06,306 Right? 915 00:43:06,307 --> 00:43:09,378 Because there are 900,000 people here at the peak. 916 00:43:09,379 --> 00:43:13,003 If you had the plague here, it would have been horrific, 917 00:43:13,004 --> 00:43:14,901 and there would be no way that, that people would have been able 918 00:43:14,902 --> 00:43:19,216 to deal with that much human remains in, in the normal way. 919 00:43:21,564 --> 00:43:24,842 If it wasn't a cataclysmic event, 920 00:43:24,843 --> 00:43:26,257 could a slow decline 921 00:43:26,258 --> 00:43:30,227 have been triggered from within the Khmer Empire itself? 922 00:43:30,228 --> 00:43:33,541 What changed for the Khmer? 923 00:43:37,235 --> 00:43:39,477 A discovery during the restoration 924 00:43:39,478 --> 00:43:41,652 of Angkor's Ta Prohm temple 925 00:43:41,653 --> 00:43:43,379 may provide a clue. 926 00:43:47,210 --> 00:43:48,694 Ta Prohm was constructed 927 00:43:48,695 --> 00:43:51,524 as a Buddhist temple in honor 928 00:43:51,525 --> 00:43:55,528 of King Jayavarman VII's late mother. 929 00:43:55,529 --> 00:43:57,564 The first step taken by our team 930 00:43:57,565 --> 00:43:59,637 was to conduct an initial survey. 931 00:44:01,708 --> 00:44:05,918 Our team discovered broken pieces of a Buddha statue. 932 00:44:05,919 --> 00:44:08,679 Once our team began digging and cleaning, 933 00:44:08,680 --> 00:44:10,750 more and more of the statue 934 00:44:10,751 --> 00:44:13,788 began to emerge from the ground-- 935 00:44:13,789 --> 00:44:17,447 more than 140 pieces in total. 936 00:44:18,759 --> 00:44:20,933 Some of these sculptures were buried, 937 00:44:20,934 --> 00:44:24,938 while others were left scattered around the temple grounds. 938 00:44:28,251 --> 00:44:33,186 Ta Prohm was not the only temple to see this kind of destruction. 939 00:44:33,187 --> 00:44:35,464 So, we're at Preah Khan temple here. 940 00:44:35,465 --> 00:44:38,398 It was dedicated in the year 1191 941 00:44:38,399 --> 00:44:40,918 to Jayavarman VII's father. 942 00:44:40,919 --> 00:44:42,540 What's on the left here 943 00:44:42,541 --> 00:44:44,094 is a series of niches where the Buddhas 944 00:44:44,095 --> 00:44:45,612 have been completely hacked out. 945 00:44:45,613 --> 00:44:49,030 And we think that this was an act of religious violence. 946 00:44:49,031 --> 00:44:52,516 What would have caused the Khmer to turn against Buddhism? 947 00:44:52,517 --> 00:44:54,345 We believe that in the 13th century, 948 00:44:54,346 --> 00:44:57,452 one of Jayavarman VII's successors, Jayavarman VIII, 949 00:44:57,453 --> 00:44:58,453 was responsible for this, 950 00:44:58,454 --> 00:45:00,973 and shifted the royal cult 951 00:45:00,974 --> 00:45:03,251 from Mahayana Buddhism back to Hinduism. 952 00:45:03,252 --> 00:45:07,013 This act was either due to religious reasons 953 00:45:07,014 --> 00:45:08,601 or even political reasons, 954 00:45:08,602 --> 00:45:12,053 as a retaliation against the reign of Jayavarman VII. 955 00:45:12,054 --> 00:45:16,402 After Jayavarman VII's golden era under Mahayana Buddhism, 956 00:45:16,403 --> 00:45:19,612 and Jayavarman VIII's Hindu backlash, 957 00:45:19,613 --> 00:45:22,580 the Khmer religion changed one last time, 958 00:45:22,581 --> 00:45:27,862 to an older form of Buddhism called Theravada Buddhism. 959 00:45:27,863 --> 00:45:29,967 The Khmer Empire was undergoing 960 00:45:29,968 --> 00:45:32,212 another major cultural and religious shift. 961 00:45:34,801 --> 00:45:36,353 King Indravarman III 962 00:45:36,354 --> 00:45:41,738 essentially switched the entire religious ideology and landscape 963 00:45:41,739 --> 00:45:43,912 to Theravada Buddhism, 964 00:45:43,913 --> 00:45:46,570 beginning during his reign in the year 1296. 965 00:45:46,571 --> 00:45:51,023 Chinese ambassador Zhou Daguan arrived at Angkor 966 00:45:51,024 --> 00:45:53,819 just as the empire moved to worshipping 967 00:45:53,820 --> 00:45:57,477 at Theravada Buddhist temples called viharas. 968 00:45:57,478 --> 00:45:59,583 Zhou Daguan saw this society 969 00:45:59,584 --> 00:46:02,310 that was in transition and changing. 970 00:46:02,311 --> 00:46:04,001 Rather than more temples being constructed, 971 00:46:04,002 --> 00:46:06,797 it was now vihara and monasteries. 972 00:46:06,798 --> 00:46:11,768 There were still construction activities after 1295. 973 00:46:11,769 --> 00:46:14,322 The type of structures, the type of temple, 974 00:46:14,323 --> 00:46:17,049 changed because of Theravada Buddhism. 975 00:46:17,050 --> 00:46:20,569 Because Theravada Buddhism only require a terrace 976 00:46:20,570 --> 00:46:24,850 surrounded by boundary stones, 977 00:46:24,851 --> 00:46:25,851 and a Buddha statues, 978 00:46:25,852 --> 00:46:27,093 and then wooden upper structures. 979 00:46:27,094 --> 00:46:29,820 So that's very simple. 980 00:46:29,821 --> 00:46:32,409 And that's what could drive a lot of change. 981 00:46:32,410 --> 00:46:36,344 The age of giant, ornate stone temples was over. 982 00:46:36,345 --> 00:46:40,451 The shift away from huge temples and elaborate ceremony 983 00:46:40,452 --> 00:46:43,213 not only meant less construction, 984 00:46:43,214 --> 00:46:47,424 but fewer monks, dancers, and religious staff. 985 00:46:47,425 --> 00:46:49,081 All this could have contributed 986 00:46:49,082 --> 00:46:50,979 to a shrinking population at Angkor 987 00:46:50,980 --> 00:46:53,257 in the 1300s. 988 00:46:53,258 --> 00:46:55,018 But would it have caused the Khmer 989 00:46:55,019 --> 00:46:59,056 to completely abandon such a vibrant city? 990 00:46:59,057 --> 00:47:02,577 Or was there another, fatal blow to Angkor? 991 00:47:02,578 --> 00:47:05,338 We don't, obviously, have a historical record 992 00:47:05,339 --> 00:47:06,650 of climate from Angkor. 993 00:47:06,651 --> 00:47:08,997 There was nobody here recording it at the time. 994 00:47:08,998 --> 00:47:11,620 So what we have to do is look for other sources of information 995 00:47:11,621 --> 00:47:12,656 that can tell us that. 996 00:47:12,657 --> 00:47:15,555 We exploited some tree ring records 997 00:47:15,556 --> 00:47:17,799 from the mountains of Vietnam 998 00:47:17,800 --> 00:47:21,182 that tell us about rainfall, in particular. 999 00:47:21,183 --> 00:47:23,391 And they tell us a really interesting story 1000 00:47:23,392 --> 00:47:25,358 about variations in weather and climate 1001 00:47:25,359 --> 00:47:29,156 during the period where Angkor is abandoned. 1002 00:47:30,157 --> 00:47:31,571 The study showed 1003 00:47:31,572 --> 00:47:33,539 a series of droughts at a time 1004 00:47:33,540 --> 00:47:35,438 when Angkor was vulnerable. 1005 00:47:36,577 --> 00:47:37,612 So those two droughts occurred 1006 00:47:37,613 --> 00:47:38,613 from about the middle 1007 00:47:38,614 --> 00:47:39,890 of the 14th century, 1008 00:47:39,891 --> 00:47:41,823 so from about 1350 onwards, 1009 00:47:41,824 --> 00:47:43,825 and they lasted for about two decades, 1010 00:47:43,826 --> 00:47:45,413 more or less, at a time. 1011 00:47:45,414 --> 00:47:47,967 So, they were really, really severe-- quite profound. 1012 00:47:47,968 --> 00:47:50,107 Nothing like we have seen in the modern era. 1013 00:47:50,108 --> 00:47:54,663 Angkor had survived droughts before, 1014 00:47:54,664 --> 00:47:57,252 but this time may have been different. 1015 00:47:57,253 --> 00:47:59,979 So, you have the sense that Angkor is very successful, 1016 00:47:59,980 --> 00:48:02,395 but it's building itself into a state of precariousness. 1017 00:48:02,396 --> 00:48:05,847 So, by the time it gets to the middle of the 1300s, 1018 00:48:05,848 --> 00:48:07,297 and you're hit with a massive drought, 1019 00:48:07,298 --> 00:48:09,471 and then a, a big wet period, and another massive drought, 1020 00:48:09,472 --> 00:48:11,888 the whole system starts to crack and come apart. 1021 00:48:11,889 --> 00:48:15,201 Fractured it, shattered it, by eroding, 1022 00:48:15,202 --> 00:48:17,859 by sedimenting or infilling canals, 1023 00:48:17,860 --> 00:48:19,619 and blowing out banks and reservoirs. 1024 00:48:19,620 --> 00:48:22,415 Doing all sorts of damage to the system. 1025 00:48:22,416 --> 00:48:26,247 You need to have the people who continue to have that knowledge. 1026 00:48:26,248 --> 00:48:29,250 Without those people, everything collapse. 1027 00:48:29,251 --> 00:48:31,908 The lidar data also reveals some failures 1028 00:48:31,909 --> 00:48:33,392 in the water management system. 1029 00:48:33,393 --> 00:48:36,257 So here we can see where a channel 1030 00:48:36,258 --> 00:48:37,775 cut through an embankment. 1031 00:48:37,776 --> 00:48:39,225 You can see that this is going 1032 00:48:39,226 --> 00:48:42,849 right through the middle of a densely occupied urban space. 1033 00:48:42,850 --> 00:48:44,990 So, this would have been devastating for the people 1034 00:48:44,991 --> 00:48:46,405 that were living here at the time. 1035 00:48:46,406 --> 00:48:47,785 And one of the other things is, 1036 00:48:47,786 --> 00:48:50,374 we can see that this failure was never repaired. 1037 00:48:50,375 --> 00:48:53,205 At some point in the 1400s, 1038 00:48:53,206 --> 00:48:57,002 the city of Angkor was largely abandoned. 1039 00:48:57,003 --> 00:48:59,590 Only a handful of farmers, monks, 1040 00:48:59,591 --> 00:49:02,904 and religious pilgrims remained. 1041 00:49:02,905 --> 00:49:05,976 Over time, the jungle covered the ancient heart 1042 00:49:05,977 --> 00:49:07,322 of the Khmer Empire. 1043 00:49:07,323 --> 00:49:12,465 For over 600 years, the seasonal floods and droughts 1044 00:49:12,466 --> 00:49:15,296 ravaged the ancient monuments. 1045 00:49:15,297 --> 00:49:18,023 Today, Cambodians have an ambitious plan: 1046 00:49:18,024 --> 00:49:19,990 restore the ancient hydraulic systems 1047 00:49:19,991 --> 00:49:22,165 and bring the water back to Angkor 1048 00:49:22,166 --> 00:49:23,373 and the surrounding area. 1049 00:49:27,102 --> 00:49:28,516 Our ancient ancestors 1050 00:49:28,517 --> 00:49:30,104 already designed and built 1051 00:49:30,105 --> 00:49:32,623 working water systems. 1052 00:49:32,624 --> 00:49:34,867 So as the younger generation, 1053 00:49:34,868 --> 00:49:39,009 our work is simply to restore and rehabilitate. 1054 00:49:39,010 --> 00:49:40,286 We are combining the use 1055 00:49:40,287 --> 00:49:43,738 of ancient technology that already exists 1056 00:49:43,739 --> 00:49:45,499 with our modern technology. 1057 00:49:49,779 --> 00:49:52,195 Restoring the channels into the barays 1058 00:49:52,196 --> 00:49:54,266 to prevent flooding and hold water 1059 00:49:54,267 --> 00:49:57,338 has been successful. 1060 00:49:57,339 --> 00:50:00,997 The Northern Baray is now full. 1061 00:50:00,998 --> 00:50:02,964 So is the West Baray, 1062 00:50:02,965 --> 00:50:08,073 holding more than 13 billion gallons of water. 1063 00:50:08,074 --> 00:50:12,042 The project to widen the canals and fill the ancient moats 1064 00:50:12,043 --> 00:50:15,356 continues, 1065 00:50:15,357 --> 00:50:19,292 including work on the moat around Angkor Wat. 1066 00:50:22,847 --> 00:50:26,436 In the same time, that system allow us 1067 00:50:26,437 --> 00:50:29,542 to save the water for the dry season. 1068 00:50:29,543 --> 00:50:32,718 It's impossible to have this level today 1069 00:50:32,719 --> 00:50:35,824 if those system are not put in place. 1070 00:50:35,825 --> 00:50:40,105 Even in the end of the dry season, you will have the same, 1071 00:50:40,106 --> 00:50:43,109 nearly the same water level in the Angkor Wat moat. 1072 00:50:44,662 --> 00:50:47,698 Angkor's legacy reaches beyond Cambodia. 1073 00:50:47,699 --> 00:50:50,322 Angkor is a location. 1074 00:50:50,323 --> 00:50:55,430 It's also a representation of a culture and a civilization, 1075 00:50:55,431 --> 00:50:57,294 the ways in which humans can flourish 1076 00:50:57,295 --> 00:50:59,296 in difficult environments. 1077 00:50:59,297 --> 00:51:02,472 It represents a celebration of the past, 1078 00:51:02,473 --> 00:51:04,750 and it represents a warning to our future. 1079 00:51:04,751 --> 00:51:06,200 But for the Cambodian people, 1080 00:51:06,201 --> 00:51:09,479 the centuries of history at Angkor 1081 00:51:09,480 --> 00:51:13,103 form a central part of their identity. 1082 00:51:13,104 --> 00:51:15,830 Through the transition 1083 00:51:15,831 --> 00:51:17,935 from the Angkorian to post-Angkorian period, 1084 00:51:17,936 --> 00:51:20,835 it's social transformation. 1085 00:51:20,836 --> 00:51:25,322 After the collapse of Angkor, it became a symbol of power. 1086 00:51:28,223 --> 00:51:29,326 For the Khmer people, 1087 00:51:29,327 --> 00:51:34,193 Angkor is an important cultural symbol, 1088 00:51:34,194 --> 00:51:38,578 a reflection of the Khmer identity and soul. 1089 00:51:40,269 --> 00:51:44,790 All the local people want to pay the respect to Angkor. 1090 00:51:44,791 --> 00:51:49,277 Angkor, for the Cambodian people, 1091 00:51:49,278 --> 00:51:51,211 it's a lot-- everything. 1092 00:51:53,144 --> 00:51:56,595 The sacred aspect of Angkor 1093 00:51:56,596 --> 00:51:58,597 never left Angkor-- it is still here. 1094 00:52:03,982 --> 00:52:06,984 It's still here today.