All language subtitles for Jungle.Atlantis.S01E01

[BIRDS CHIRPING]

NARRATOR: 1,000 years ago,

one of the world's
greatest civilisations

built an empire here in Cambodia.

It dominated Southeast Asia
for nearly 600 years.

And was the biggest superpower
the region has ever seen.

Their capital was the great city
of Angkor.

This was an extensive kingdom.

Its power surpassed
the modern-day borders.

An empire this great is something
to be truly marvelled at

and to have so much remaining
from that time,

it's just a remarkable thing
to witness.

NARRATOR:
Starting as a nation of rice farmers,

the Khmer people would go on
to build some of the most

spectacular structures
of the Medieval age.

The pinnacle of their culture
was the great temple Angkor Wat,

still the largest religious monument
in the world.

But 500 years ago, the Khmer kings
abandoned their capital.

The city of Angkor was quickly
devoured by the jungle.

For over 100 years,
scientists have been unable

to explain why one of the world's
most powerful civilisations

abandoned their city.

Now, an international team
of experts

is trying to solve one of the great
mysteries of the Medieval age.

As archaeologists,
we're interested in questions of,

who the people were
who built these temples,

where do they come from?
How did they survive?

What did their cities look like,
and what happened to them?

NARRATOR: Using a revolutionary
laser-scanning technique

called LIDAR,

they're looking beneath the jungle
to uncover the secrets

of this extraordinary civilisation.

JEAN-BAPTISTE:
This is the royal palace,

the civil centre of that ancient city

where the king would live.

It's amazing. Really amazing.

NARRATOR:
For the first time in 500 years,

LIDAR is helping to reveal
the lost metropolis

of the people who built Angkor Wat.

DAMIAN: Some colleagues of mine
have described it as, essentially,

a scientific revolution.

NARRATOR:
We are now closer than ever before

to an understanding
of how the Khmer people

came to dominate Southeast Asia.

And why their great city
ultimately collapsed.

[CRICKETS CHIRPING]

NARRATOR: Deep inside
the stone chambers of Angkor Wat,

the annual candle ceremony,
Meak Bochea.

[CROWD CHANTING]

A Buddhist ceremony
to purify the mind.

WAYNE:
Many people think of Angkor Wat

as a dead monument,
a place that was abandoned

and the tourists come here
just to admire its architecture.

But, you know,
it's a living monument.

It's a place which has real life
in amongst the people of Cambodia.

It's an amazing place,
a special place.

Angkor Wat is a place full
of surprises.

NARRATOR: Angkor Wat
is one of the most beautiful

and mysterious buildings
in the world.

NARRATOR: Five huge towers
shaped like lotus buds,

surrounded by a six-kilometre moat.

A temple of perfect symmetry

covering an area
of two square kilometres.

This is one of the wonders
of the Medieval world.

What I feel when I see Angkor Wat
is, I am impressed

by the coming together,

the collectivity of a great many
kinds of genius here.

The genius of the mathematician,

the genius of the artist,
the genius of the architect,

the genius of the engineer
and the genius of the people

who aspired to build these things.

Who cannot be in love with Angkor?

NARRATOR: The temple was constructed
nearly 1,000 years ago.

In Europe at that time, the Normans
would spend over 100 years

building their vast cathedrals.

The Khmer people completed Angkor Wat
in under 40.

And that included two kilometres
of intricate engravings...

with nearly 2,000 celestial
dancers from Hindu mythology...

everyone unique.

In the 12th century,
this was the spiritual

and administrative heart
of the city of Angkor.

It would come to rule an empire

that stretched a million square
kilometres across Southeast Asia.

Every year, more than two million
people are drawn

to the Khmer's
archaeological treasures.

They drive a tourist industry worth
more than two billion dollars a year,

nearly twenty percent
of Cambodia's entire economy.

But the people who built this temple

and the city around it,
remain an enigma.

Most evidence for how the Khmer
people built their city

has been lost or swallowed
by the jungle.

WAYNE: Archaeologists and historians
have been studying Angkor

for about 150, 160 years.

But, little was known
about the actual people

who inhabited these spaces.

The great stone
buildings were one thing,

but not everyone lived
in the temples.

And so, more and more
throughout the 20th century,

the questions were being asked,
what about the everyday people?

Who were they? Where did they live?
What was their life like?

NARRATOR:
Now, a new project

is attempting to solve
some of these mysteries...

by using a revolutionary technology
called LIDAR.

[BLADES WHIRRING]

OK, we're airborne above Angkor.

NARRATOR: Damian Evans,
from the University of Sydney,

is leading a team
of international experts

who are peeling back
the layers of forest

to reveal the secrets of the people
who built Angkor Wat.

DAMIAN: Most of the city
that existed here 1,000 years ago

would have been made
of very, very flimsy material.

Just light pieces of wood
and thatch and so on.

Uh, within one or two years,
that stuff just rots away completely.

We can still make out these very,
very subtle traces

of where they used to be,
by analysing the surface topography

of the landscape.

NARRATOR: LIDAR works
in a similar way to radar.

It scans the ground by sending out
a million laser points

every four seconds, and analysing
the information reflected back.

The time it takes for each pulse
to break through the trees,

hit the ground
and return is measured.

The results are then mapped.

The shapes revealed
are the footprints of structures

from the long-lost capital
of the Angkorian empire.

DAMIAN: We get this data back
to the office, we can click a button,

strip those trees from the picture
and really, for the first time,

see those cities of Angkor emerge
in incredible detail

on the computer screen
in front of us.

NARRATOR: The jungle is removed
in an instant.

The LIDAR data renders
an outline of everything

on the surface of the land.

The glory of Angkor Wat becomes
a ghostly outline of digital points.

But LIDAR also reveals
the shape of the old city.

Angkor Wat is shown to be
surrounded by the ghostly outline

of a vast metropolis.

And we can use this data
to re-build the city of Angkor

as it would have looked
over 900 years ago.

Shadowy lines that were once roads...

canals long since swallowed
by the jungle...

and the outline of thousands
of houses, monasteries and palaces.

It's an incredible leap forward for
us to be able to use this technique.

You can imagine that doing things
by hand on the ground

uh, is a process
that would take decades, basically.

Now, using these new techniques,
we have the opportunity

um, to do a bit of flying, just
a few hours, to take that data back

to the office and with a few clicks
of the button,

we see entire urban landscapes
unfolding on the screen

in front of us for the first time.

NARRATOR: The LIDAR imagery
shows that central Angkor

was organised into regular-sized
city blocks...

and that many of the dwellings
of the Angkorian era

were clustered around thousands
of ponds.

LIDAR is an incredibly valuable tool,

because what it allows us to do
is to breathe life

back into that landscape.

And, for the first time, it reveals
with exceptional clarity

these vanished cities
that surrounded the monuments,

and allows us to create a new image
of Angkor as a place

that was teeming with life
and full of activity.

NARRATOR: LIDAR confirms
that the city spanned an area

larger than the whole
of New York City.

In the 12th century,
when Angkor Wat was being built,

London had a population of 18,000.

It's been estimated
that Angkor had a population

approaching three-quarters
of a million.

Until the 19th century,

Angkor was the most extensive city
in the world.

Bringing the old capital back to life

was only one
of the project's ambitions.

LIDAR has also started giving
revolutionary insights

into the origins of the Khmer Empire.

Since 1999, French archaeologist
Jean-Baptiste Chevance

has been studying the Kulen Hills,
forty kilometres north of Angkor.

He has dedicated his life
to uncovering the remains

of a 9th-century Khmer settlement.

It's a tough, simple existence.

I've been driving around for years,
so, I know the place pretty well.

I feel comfortable
with the local people,

with the research, with the temples.
It's part of my life.

The dirt bike is fun.

It's the easiest way to go
from A to B.

Especially in rainy season,
roads are turning into rivers,

so, you have to be cautious.

[ENGINE TURNS OFF]

NARRATOR: Historians believe
that the Khmer Empire began here

in the Kulen Hills,

three-hundred years
before Angkor Wat was built.

Before the LIDAR project,

Jean-Baptiste used
conventional archaeology

to piece together a picture
of an early Khmer capital.

This is Rong Chen temple.

NARRATOR: Rong Chen sits on one
of the highest peaks

in the Kulen Hills.

At the time it was being built,

Anglo-Saxon Britain was being
attacked by the Vikings.

Rong Chen is the only mountain
temple in Phnom Kulen.

A temple made of different levels,
like a pyramid.

It has always been considered
as the centre of the religious city.

Nobody has really studied
and maintained this temple,

because Angkor was attracting
most of the attention.

NARRATOR: Inscriptions in temples
built 200 years later

suggest that Rong Chen
was the religious heart

of a new capital
called Mahendrapravata.

And it was built for a powerful
Khmer king, Jayavarman II.

Before his rule, Cambodia was
a collection of small kingdoms

ruled by local lords.

Eleventh-century inscriptions

suggest that Jayavarman came
to dominate the area

by declaring himself
to be a special mediator

between God and man.

JEAN-BAPTISTE:
Jayavarman II was the first king

to unify those kingdoms.

He also installed a new cult
of the god-king,

which made him even more powerful.

That cult was perpetrated by all
the kings that were following him,

and therefore, Jayavarman II
has always been referred

as the king who was unifying
the Khmer kingdom

and starting the Angkorian period
leading to Angkor Wat.

NARRATOR: With only a few ruins
and inscriptions to go on,

understanding the early days
of the Khmer Empire

has always been difficult.

And for many years, archaeological
digs here were also impossible.

From 1975 to 1979,
the Communist Party of Cambodia,

the Khmer Rouge,
established a totalitarian state

based on the teachings
of Mao Tse Tung.

Under the leadership
of dictator Pol Pot,

they ruled by terror,
rejecting urban culture

and trying to build a self-sufficient
agricultural society.

By the end of Pol Pot's rule,

more than a million-and-a-half
Cambodians had been killed.

Many more were left
with permanent injuries.

The Kulen Hills was one of the last
strongholds of the Khmer Rouge.

Until '96, it was completely
impossible to come here.

At that time, the Khmer Rouge were
occupying an artillery battery

just behind this temple.

As a Westerner, you would've been
kidnapped or killed.

Even the Cambodians
couldn't come here,

it would have been
just too dangerous.

NARRATOR: Today, the Kulen Hills
remain heavily mined.

So, this part of the Khmer Empire
is one of the least explored.

Jean-Baptiste's work
and his participation

in the LIDAR project
is changing that.

Laser information reflected
from the surface of the Kulen Hills

revealed the shadow
of Jayavarman's city

for the first time
in more than 1,000 years.

The LIDAR results showed
that Mahendrapravata

was a much more sophisticated city
than anyone had expected.

It also covered a much greater area.

JEAN-BAPTISTE: We found
the urban network, which is massive,

which is covering at least
eight kilometres by four.

What you have here is the area
which was covered by the LIDAR.

It's very, very surprising, because
we passed over those sites for years.

This is a modern road
we use almost every day,

but you go in the field
and you barely see things.

We knew that in Kulen Hills, you had
a high concentration of temples,

one of them being
the mountain temple,

but we didn't really know
how it was connected together.

We didn't have the link between
all these religious sites.

The LIDAR give us a complete vision,
but in a way that is so spectacular

that we couldn't really believe it.

When we saw the result, that was
like a big surprise, to be honest.

NARRATOR: The LIDAR survey
provides precise information

about where to look for the remains
of further hidden structures.

This is a GPS, which allows me
to know exactly where I am,

and we have downloaded
the LIDAR result on it,

so, I know exactly where I am,
according to the LIDAR.

And I can check every feature,

I can check everything
going back on the field.

NARRATOR: In an area
cleared of mines,

Jean-Baptiste is following up
LIDAR data

that suggests the presence
of an unexpected structure.

JEAN-BAPTISTE:
This is what I was looking for.

We have, actually, here two termites.

One here and one over there.

They're all in a line
and this is not natural.

NARRATOR: Termites don't build their
mounds in straight lines in nature,

yet here, there are six of them.

The LIDAR map suggests
that the termites built their nests

on the remains of an earth bank
built in the ninth century,

at the edge of a medieval Khmer road.

JEAN-BAPTISTE: So, we're standing
exactly on the blue arrow here.

What we have beneath
is the LIDAR images,

and on the top, we have highlighted
the main road.

Uh, so, if you go this way,
you will see that line

that we have on the screen here,

and this is exactly the bank
of that massive road.

NARRATOR: The termites are unwitting
markers of a vast boulevard.

Eighty metres wide,
six kilometres long.

JEAN-BAPTISTE: The size
of these roads are amazing.

You could have a plane landing here,

you could have dozens
of elephants running

and probably hundreds
if not thousands of people.

It would have been
a very impressive sight.

NARRATOR: The LIDAR images
of Mahendrapravata

reveal that Jayavarman II
began the construction

of a remarkable city.

The Khmer people managed to clear
tens of kilometres of jungle,

to begin the construction
of their new capital.

The LIDAR survey reveals a huge
centrally planned metropolis.

Canals...

reservoirs...

dams...

and a network of giant boulevards

covering an area of at least
thirty square kilometres.

[ENGINE TURNS OFF]

JEAN-BAPTISTE:
We're actually here on a dam,

which is a massive dyke
blocking the valley,

uh, one of the main valleys
of the Kulen Hills,

and it's running over 300 metres

and blocking, right behind me,
a huge reservoir.

It's covered now by vegetation,
it's a big swamp,

but at that time, you have to imagine
water all over.

NARRATOR: LIDAR allows us
to re-imagine this early Khmer city.

A huge reservoir
of eight square kilometres

to sustain a rapidly growing
population.

DAMIAN: In a sense, you could say

that LIDAR is literally
and figuratively

shining a light into these forgotten
aspects of Khmer history.

The focus has always been
on the temples and the monuments

and these elite aspects
of Khmer civilisation.

For the first time, we can consider
the bigger picture

and put people back

and consider these cities
in all of their complexity.

NARRATOR: Constructions like the dam

show that the city was ruled
by a leader

who could plan and deliver
huge engineering projects.

JEAN-BAPTISTE:
You have a massive structure

irrigating and controlling
the water system up here.

This required a huge amount
of labour.

Therefore, whoever is behind this
is quite strong in terms of power,

in terms of politics.

NARRATOR: A powerful political system
was also needed

to help overcome one of the Khmer
people's major challenges.

[THUNDER RUMBLING]

A metre-and-a-half of rain
falls in the monsoon

between May and November,

nearly 90 percent
of the annual total.

And then, after six months of deluge,
the long dry season begins.

Temperatures hover around 40 Celsius
and for six months, nothing grows.

If the crops fail during the wet
season, famine follows.

[BIRDS CHIRPING]

[WATER FLOWING]

The Khmer were obsessed with water,
and at this river in the Kulen Hills,

they sought to sanctify it

by creating an elaborate
underwater shrine.

These carvings in the rock
of the river bed

were made in the 11th century,

two-hundred years after Jayavarman
founded his capital.

The shapes represent Hindu symbols
of male and female fertility.

This is one of my favourite places
here because it's beautiful.

It's a river bed which is completely
carved for more than one kilometre

carved with this symbol of the Khmer
and the Indian mythologies.

This is a very unique place.

NARRATOR: These intricate designs
were carved to preserve life.

The water running here
goes to the Angkor region.

This sacred carving brings a kind
of spiritual value to the water,

going down to the reservoir
and to the rice crops.

The whole idea is quite magical.

NARRATOR:
Rainwater from the Kulen Hills

flows over these carvings
down to the Cambodian plains.

The sanctified water sustained
the staple of life

for an entire people.

Ninety years after Jayavarman

made Mahendrapravata
a capital of his kingdom,

the administration moved here,
to Angkor.

Landscape archaeologist, Scott Hawken

has been studying how rice farming
shaped the new capital.

SCOTT: Mostly for the history
of research on Angkor,

people have been studying
temples, and...

the magnificent structures that
everybody talks about and notices,

but you can't understand the city
until you go to the rice fields.

It's really interesting to start off

with the smallest elements
of the archaeological landscape,

the humble rice fields,

and then to build up a picture
of this mighty, mighty city, um...

that was over 1,000 square
kilometres in size.

NARRATOR: The rice harvest here,

has always depended
on a secure water supply.

I use satellite imagery,
aerial photography

and map the rice fields
and the particular patterns

that they make within the landscape,

then, I can understand

from these patterns,
how the city developed over time.

[SPEAKING IN KHMER]

SCOTT: He's been farming
these rice fields here for many years

and all this water comes
from a local reservoir just upstream,

which is 1,000 years old.
So, it's remarkable.

These rice fields have been watered

by a reservoir that his ancestor
built 1,000 years ago.

NARRATOR: Scott's work
shows that the solutions found

by Angkorian engineers
are still used today.

A successful harvest

still depends on careful management
of the monsoon waters.

SCOTT: Rice is a very demanding crop.

You really have to control water
in a very precise way,

and this takes a lot of labour
and energy,

and if you don't do this,
then the rice crops will fail.

NARRATOR: At first, the people
of Angkor tried to reduce

the chance of failure
by building their city

close to an enormous
natural body of water.

Every year, these fields are
nourished by the rising waters

of the largest lake
in Southeast Asia.

Tonle Sap, the Great Lake.

[BOAT ENGINE REVVING]

NARRATOR: Tonle Sap is still critical

to the survival of nearly a quarter
of all Cambodians, today.

SCOTT: It's only when you get down
and are on the lake itself

that you really understand
how vast it is.

It's just enormous.
It's like an inland sea.

[BOAT ENGINE REVVING]

NARRATOR: Even in the dry season,

the lake covers nearly two percent
of the surface area of Cambodia.

During the monsoon,
it expands to cover

almost ten percent
of the whole country.

SCOTT: The edge of the Tonle Sap
is a tremendously fertile resource

for around a million people.

As the lake swells
and then as it shrinks,

it leaves this rich layer of silt.

NARRATOR: But the people here
had little control

over the dramatic extremes

that Tonle Sap imposed
on their lives.

During every monsoon,
the water rises by ten metres.

People living here today
are still forced to adapt

to the lake's natural cycle.

So, this fascinating village here,
Kompong Phluk, is perched up

in the air on these enormous stilts,
ten metres high in the sky.

And this tells us something
very interesting

about the local environment.

In the wet season,
the waters here rise up,

so, this village in the air becomes
a village in amongst the water.

It's a remarkable village,
it's really surreal,

it's extraordinary.

NARRATOR: People in the Angkorian
era faced the same challenges.

There are two ways
that a society can face

these dramatic climatic conditions
of rising and falling water levels.

It can adapt,
like this village has, um...

or it can actually take control
and go beyond living on the margins

and really try to change
the ecosystems and the environment

to suit the society itself.

NARRATOR:
The people of medieval Angkor

chose to take on the environment

and to move from managed subsistence
to a mastery of the landscape.

If you're a subsistence farmer,
it's a very precarious existence.

So, the key, really, to surviving
in this kind of landscape

is to develop technologies
to overcome that inherent limitation.

NARRATOR: The people of Angkor
developed new engineering skills.

And nearly 1,000 years ago,

they built two huge reservoirs
known as barays.

DAMIAN: Right now, just below us
is the West Baray,

the largest of the reservoirs
of the Angkor period.

Uh, it's an absolutely
huge construction,

it's eight kilometres long
on its north and south sides,

and two kilometres long
on its east and west sides.

It's an incredibly impressive piece
of engineering.

NARRATOR: The West Baray

is the largest hand-dug reservoir
on the planet.

It can hold over 48 million
cubic metres of water.

It's estimated that 200,000 people

were needed to construct
its high embankments.

SCOTT: It's really remarkable to
stand on the edge of the West Baray.

It's just an enormous, beautiful lake

built to precision engineering
standards.

But it's not just a functional
piece of infrastructure,

it's also really humbling and moving
how beautiful it is.

NARRATOR: Nine-hundred years
after the baray was completed,

its waters are still used
to irrigate the surrounding fields

during the dry season.

SCOTT: The West Baray is really
the pinnacle of the Khmers'...

um, ability to transform
their environments...

and attempt to neutralise
the flux of the monsoon.

If you look at society today,
we're all about

risk management, climate change.

They were doing the same thing
back then,

trying to manage these droughts
and to even out the disturbances,

so that the local population
wouldn't revolt

and the kings could manage
their society.

NARRATOR: LIDAR work across Angkor
shows how the Khmer people

transformed this area with advanced
hydraulic engineering.

The elaborate network of canals
and reservoirs

meant that they could now grow crops

far away from the area irrigated
naturally by Tonle Sap.

From an engineering point of view,
what was achieved here

is absolutely incredible.

They moved phenomenal amounts
of the landscape from different parts

of Angkor to other areas
and, basically, terraformed

the entire plane into
a completely artificial landscape,

in order to release themselves from
these limitations,

uh, of relying on the rainfall
for one crop of rice per year.

NARRATOR: A Chinese diplomat,
writing in the 13th century,

marvelled at the Khmers' ability

to harvest three or even four crops
a year from their irrigated lands.

Once you've solved the problem
of water supply,

you've solved the problem
of food security.

What you've done then
is provided an extremely solid

economic foundation
for the growth of the empire.

The king can turn his attention
to things like empire-building,

to warfare, to temple-building
and so on.

And so, it's a complete
transformation, actually,

in the way that things are done
in Cambodia.

This mastery of the natural
environment is one of the reasons

for the rise and the success
of the Khmer Empire.

NARRATOR: These engineering projects

demanded huge investments
of labour and expertise.

The whole society had to contribute
time and resources

to build the system of canals
and reservoirs.

Ten kilometres from Angkor Wat
is Preah Ko temple.

Inscriptions on the walls
of this ninth-century shrine

tell how the Angkorian kings

used the temple system
to tax the population.

Archaeologist Julia Esteve has spent
the last ten years translating them.

Most people think that temples
are only religious entities,

but, you have to understand,
the king, Jayavarman II,

the founder of the Khmer Empire,

was at the same time a god

and used the temples to strengthen
his economic and political power,

and so, these temples are not only
religious entities,

but also, economical
and political tools.

NARRATOR: Temples had administrative
as well as religious functions.

No coins have been found
from this period.

It's thought the economy was run
by exchange and barter,

with a duty to make donations
to the temples.

There were contributions coming from
the lower strata of the society

made by rice farmers.

They would donate some of their time
to the temple

in order to give some rice
to the god.

With these kind of donations,
we see another side of the temples,

and through the temples, the king
would develop a system of taxation.

NARRATOR: Inscriptions
from the temple walls

suggest that payments took
a surprising variety of forms.

JULIA:
This is one of the inscriptions.

And it's a fascinating text because
it gives us the list of goods

donated to this particular shrine.

We have, for example,
an umbrella-holder, a spice-grinder.

Also, a garland-maker.

And, along with this, we also have
workers that would give labour.

NARRATOR: But Julia's work
has revealed

that people would also give up
their own children.

JULIA: We can see children.

Uh, there is here a baby,
and, uh, over here

there is a child
who is at the age of running.

So, children were donated to a temple
or were considered as future workers,

uh, to help all the people
who were here to serve the gods.

NARRATOR: The inscriptions reveal
a highly hierarchical society

built on forced labour.

Julia's studies show
how the Angkorian kings

built a network of religious shrines
to consolidate their imperial power.

And LIDAR reveals the footprint
of these religious buildings

across the medieval city.

DAMIAN: LIDAR isn't just useful
for areas that are covered by forest,

we also flew the instrument over
large areas of open landscape.

And even in those areas,
we're getting tremendous new insights

into archaeological sites

that lie out in the open rice fields.

There are some things that just jump
out of the imagery at you.

There are some classes of temples

that have a very,
very distinctive layout.

NARRATOR: Five kilometres
from Angkor Wat,

close to the edge
of another huge reservoir,

the ghostly footprint of one
of these buildings

appears on the LIDAR map.

Three-hundred metres in length
and clearly broken

into three sections,
these were ashramas,

part monastery, part tax office,
part school.

JULIA: The building behind me
is an ashrama,

and we know
that there were communities

of religious people living
in the ashramas,

but we also think that some people,
if they could afford it,

could send their kids
to get educated,

maybe, uh, learn how to read.

NARRATOR: These ashramas reveal
the growing sophistication of Angkor.

Some were now wealthy enough

to invest their time in leisure
and learning,

and their religious buildings
were taking on a grander scale.

We're able now to say
that they all had the same layout,

for those in Angkor at least.

And they were built
around a central sacred building

where the religious people
would gather.

NARRATOR: Many ashramas were built
on the edges of Angkorian territory,

a symbol of Khmer power...

and a demonstration
that the land around

belonged to a strong
and unified empire.

We know from writings from the time

that the king needed money and a lot
of people to build ashramas.

The building of more than 100 came
at a period of great economic growth.

The king who built these ashramas
all over the country

wanted to put his stamp
on these lands

by saying, "This is my kingdom.
I'm a strong king.

I'm the best of the kings.
I'm the king of the kings.

And now, these lands are mine."

NARRATOR:
By the end of the 11th century,

Khmer lands stretched across
the modern-day borders of Vietnam,

Laos and Cambodia.

The Khmer Empire now dominated
the region.

Mitch Hendrickson, an archaeologist
from the University of Illinois,

has been studying how the Khmer
expanded beyond today's borders

of Cambodia.

We're actually following along
the northwest road,

which connects Angkor
to the site of Phimai,

which is in modern-day Thailand.

The road extends roughly 280 km,
so, we're really following

in the footsteps of people
from 1,000 years ago.

NARRATOR: The Khmer were
the only people

who built roads in Southeast Asia
at this time.

By the 11th century,
they'd built 1,000 kilometres

of roads across the region...

a network that stretched to every
part of their growing empire.

The ultimate result
of this road network

is that it enabled the Khmer
to become a regional superpower,

enabling them to branch off into
different parts of Southeast Asia

and led to their ultimate control
over mainland Southeast Asia

for about 200 years.

NARRATOR: Ox-drawn carts were used

to carry copper, iron and food
to the capital.

As the empire expanded,

trade improved the quality of life
for the people of Angkor.

Today's travellers

would have recognised
some of the roadside developments.

Forty kilometres from the capital,
a medieval rest stop,

part temple, part restaurant,
part refuge.

MITCH: This is an excellent example
of the type of infrastructure

and the desire to create support
for travellers

moving in and out of Angkor,
traders, pilgrims...

There would've been many people

who would have stayed here,
seeking shelter from bandits

or just to get some water
from one of the nearby ponds.

NARRATOR: Along this road alone,
there are seventeen rest areas

each spaced a day's walk,
about 20 kilometres, apart.

Today, there's also
an international frontier.

MITCH: So, here we are
at the modern-day border

between Cambodia and Thailand.

Of course, 1,000 years ago,
during the peak of the Khmer Empire,

Angkor's influence actually extended
into this region.

If I can find my passport...

NARRATOR: Imperial expansion
into new territories

also brought conflict and rebellion,

and Khmer kings were capable
of mustering huge armies.

Carvings at Angkor Wat show a Khmer
army on the march.

Thousands of soldiers able to travel
fast to wherever trouble flared.

We're actually off to a temple
now, that commemorates

the actions of one of the local lords

who helped put down a rebellion
for one of the Khmer kings.

MITCH: We're here at Phnom Rung...

one of the most impressive temples
on the edge of the Khmer Empire.

NARRATOR: Deep in enemy territory,

this temple was extended to mark
a Khmer leader's victory

over a local rebellion.

The large proportion of this
temple that we see today was actually

an embellishment that was made
in honour of that particular lord.

So, we have
this interwoven connection

between the civil conflict
and external expansion,

which is interconnected
with these road systems.

NARRATOR: Beyond Phnom Rung temple,

the road continues through
what is now northeast Thailand.

MITCH: The northwest road
that we're tracking right now

is a little bit different from all
the other of the Angkorian roadways

which brought what we think are more
precious commodities such as metals.

NARRATOR: The principal cargo
passing along this road

was a vital commodity.

The Khmer's great northwest road
leads to a giant open mine.

It's still in use today.

MITCH:
So, this is one of the reasons

why the Khmer travelled hundreds
of kilometres away from Angkor.

Salt.

What we're standing on now
is a salt plain that we think

was probably used back
to about 500 BC, during the Iron Age.

The salt would have been extremely
important for so many reasons.

We know that without salt,
the human body can't survive,

and rice is one of the least
saline of the cereal crops, so...

it was very significant
from a physiological perspective,

but, more significantly,
we know that salt tastes good.

So, from the peasants to the elite

and even the king,
they would have desired this salt.

NARRATOR: Then, as now,
salt was an important preservative.

For a good chunk of the year,
you can get fresh fish,

but in the rest of the year you need
to maintain your source of protein,

and the way that the Cambodians
did it at that time

was to create this lovely dish
called prahok.

And prahok is essentially
the salt from here,

taken down there, to ferment this
lovely and extremely appetising...

fishy paste,

that doesn't look good but I'm going
to give it a little taste,

just to see how it goes,
so, let's try and find a bit.

Give it a whirl.

Whoof!

[GASPS]

Woah!

[GRUNTING] Aw, man!

[SIGHS]

NARRATOR: By the late 12th century,

three-hundred years
after Jayavarman united the kingdom,

the Khmer had built the biggest
empire ever seen in Southeast Asia.

And then a new king came
to the throne, Suryavarman II.

His story is one of the best-known
in Khmer history,

partly because of the reliefs
carved into the walls of Angkor Wat.

Here, we have Suryavarman II
in all his glory,

probably the first time that a Khmer
king had been depicted in life.

He's surrounded, here, by his court.

We have the nobles,
the Brahmin advisors,

and all around, there's a scene
which takes place in a forest.

There are animals cavorting around.

There's are procession of people,
women carried in palanquins.

Soldiers... a scene
of utter prosperity.

It looks fantastic, it's beautiful.

NARRATOR: But this peaceful scene
contrasts with the legend

of how Suryavarman II became king.

It's said that he stole the throne

by raising an army
against his aged uncle,

the Khmer king,
and killing him with his own hands.

This section of Suryavarman's
army has quite a unique body of men

and they're wearing
very distinct uniforms.

An inscription actually
identified them as being Siamese.

So, this is one of the first
depictions of the Thai people.

What it actually shows us is that
Suryavarman was drawing mercenaries

from the extent of his empire,
to fight for him.

NARRATOR: After the battle,

Suryavarman brought his men back
to Angkor,

to work on the most important
building project of his reign,

the biggest religious monument
the world had ever seen.

It would draw on everything
the Khmer people had learned

about architecture
and temple-building.

Former UNESCO regional advisor,
Richard Engelhardt has spent

decades studying Angkor Wat.

RICHARD: Once he became the king,
Suryavarman II imposed a great peace

over the entire empire,

so, he built this temple
as a way of saying,

"This is the stability that I wish
to impose upon our land,

and this stability is going
to continue and continue forever."

It's the real pinnacle
of the achievement of Khmer art.

NARRATOR:
Suryavarman wanted his Angkor Wat

to eclipse everything
that had gone before.

RICHARD: We have to remember
that this is a temple to the god,

and the god needs a universe
populated with beautiful things,

with beautiful women,
beautiful goddesses,

beautiful animals, and so,
they needed a vast canvas

on which to sculpt
all of these magical creatures.

They did this by bringing these
huge blocks of sandstone

here on site, fitting them
together almost flawlessly.

There is no mortar, there's no
mortar anywhere at Angkor.

They fit the blocks together very,
very precisely.

Look, look, here's
the sandstone blocks.

You can almost not see the join,

you certainly cannot even
put your fingernail between it.

NARRATOR: All the technical expertise
and wealth of the empire

was channelled into this
spectacular building.

Most striking of all was the scale
of the construction.

Angkor Wat covers an area
more than four times larger

than the Vatican City.

And this created huge challenges
for Suryavarman's engineers.

During the monsoon, the land
becomes saturated and expands.

After the monsoon,
it dries out and contracts.

RICHARD: How do you build high
with such heavy material

as this sandstone?

Well, look behind the facade
and what do you see?

You see that it's filled
with this very lightweight,

porous material called laterite.

It's a kind of ancient breeze block.

NARRATOR:
Laterite was a core building material

of all Khmer temples,

stretching right back
to the Kulen Hills.

Now, it was being used to help solve

the Khmer's greatest
engineering challenge.

This building is much, much lighter
than you might think it is.

The weight of the building

is not pushing, pushing down
and pressing out on the earth,

but instead, is rising up and you can
build and build and build

almost as high as your imagination
lets you build.

NARRATOR: But Richard Engelhardt

thinks that the use of laterite
was only part of the solution.

He believes that Angkor Wat
is still standing today

because of the water
surrounding the great temple.

RICHARD: In the ideal Khmer
structure, you cannot separate

the building from the moat.

They are inextricable.

They are symbiotic and you cannot
have one without the other,

both in the terms of the design
and the conception

of what we are building

and the civil engineering features
of it.

Now, the Khmer were great artists,

they never did anything
that wasn't beautiful,

but the real purpose
of the moat is not for decoration.

NARRATOR: The construction
of the moat surrounding Angkor Wat

was a huge operation.

It's estimated, labourers removed
enough silt and sand

to fill St Paul's Cathedral
ten times over.

Its perimeter stretches nearly six
kilometres and is 200 metres wide.

RICHARD:
Then, the moat fills with water.

Water is heavier, it's more dense
than laterite and earth,

so, the weight of the water
is actually heavier

than the weight of the materials
you've taken out.

NARRATOR: Richard believes the weight
of the water in the moat

pushes back against the downward
force of the stone temple.

RICHARD: The moat is essential

to the success
of the entire structure.

Without the moat,
the structure could not stand.

The two are completely part
of one holistic engineering system.

NARRATOR: The Khmer had become
masters of the monsoon.

Angkor Wat was
an engineering masterpiece.

Everything the Khmer had learned
over hundreds of years

of temple-building and engineering
great water projects

came together in the construction
of the jewel of their civilisation.

RICHARD: Through hundreds of years
of experimentation

and gradual augmentation,

we find that moving from a very,
very simple rice paddy

to this extraordinary expression

of both civil engineering genius
and an ability to communicate

through the symbolic meaning
of Angkor,

this is what is so extraordinary
about this particular monument.

Absolutely, a stroke of genius.

NARRATOR: The LIDAR project
is enhancing our understanding

of the Angkorian empire

and shedding new light on
the great civilisation that built it.

But it has also uncovered
new mysteries.

Even though LIDAR has in,
in some senses,

transformed our vision of Angkor

by giving us
new insights into the cities,

there are a couple of things

which really took us completely
by surprise.

NARRATOR: Emerging
from the LIDAR data

by the side of Angkor Wat's moat,

the outline of eight
huge coiled shapes,

partly obscured
by the remains of a canal...

each one, more than 700 metres
in length.

Nothing like them
has ever been seen before.

In terms of the features
that we can see in the LIDAR,

those are definitely
the most striking.

You wouldn't know it
just to look down there,

you basically can't see
anything from above except forest

right next to the moat
of Angkor Wat, right there.

NARRATOR: These shapes have remained
hidden for hundreds of years,

right next to one of the area's
busiest roads.

We've launched
a campaign of excavation

and closer study
onto these features

to try and really come to terms
with what they might be.

NARRATOR: A team
of Cambodian archaeologists

is excavating a section
of one of these coils.

They're looking for any physical
evidence, tools or pottery,

that might suggest
why they were built.

DAMIAN: Some people have speculated
that they're gardens,

that they're used for agriculture,

perhaps, um... that they have some
sort of ritual or symbolic dimension.

NARRATOR: All the excavations
so far have proved inconclusive.

No clues about their meaning
or function have been found.

It's the nature of the game
that there's not much certainty here.

We might never understand
fully what these things are.

And I guess, as archaeologists,
sometimes we,

we just have to resign ourselves
to that reality.

NARRATOR: Angkor Wat marked the high
point of the Khmer's artistic,

architectural and engineering skill.

It's a great symbol of a civilisation

that grew from the rice paddies
of the Kulen Hills

and came to dominate the region.

WAYNE: Angkor Wat is a peak
of Khmer society.

It was a statement
of where they'd come from

and where they were heading to.

NARRATOR: LIDAR is revealing
the epic scale and sophistication

of the Khmer capital,

and helps to explain
how the Khmer people

transformed their landscape
and turned rice into gold.

Angkor is totally unique,

and the things that were achieved
here, were unparalleled

throughout all of human history.

NARRATOR: In the next programme,
a vast new temple-building project,

the Khmer Empire's great
metropolis faces destruction.

And LIDAR helps explain
why the Khmer people

allowed their capital
to be devoured by the jungle.