Original subtitles

I'm in China, where I uncover a mystery that baffled ancient Rome.

Somewhere out there is the secret of silk.

I walk in the shadow of Marco Polo across a haunted desert...

I can only hope they aren't the graves of people

who tried to cross the desert by camel.

..track the real Indiana Jones into the wild frontier lands...

We should pull over and see if we can have a look.

(DOGS BARKING) Oh, whoa, whoa.

..and reveal archaeological treasures lost for centuries.

The Silk Road is full of dangers.

I'm David Baddiel. I'm on the adventure of a lifetime...

Whoa!

..retracing the steps of merchants, warriors and pilgrims

along the largest trade route the world has ever known,

the Silk Road.

As a writer and comedian,

I'm fascinated by people and their stories.

These are amazing.

And the Silk Road is one of the greatest human stories of them all.

Yay!

It's got everything - religion, culture...

How do I look?

..music, war.

Now I want to live that story.

I was born to this.

It will push me to my limits.

We have got a bit of a situation.

There have been reports of landslides.

This monumental network stretches

across some of the toughest terrain on Earth.

It's like a sadistic army exercise.

The Silk Road witnessed the rise and fall of empires

and shaped the modern world as we know it.

The Silk Road began here.

It's here that traders from China started going out into the world

and selling their goods, primarily silk...

..and from that, international trade was created.

2,000 years ago,

Xi'an was one of the largest and most popular cities in the world,

so it's no surprise that it became the gateway

to history's most famous trade route.

The Silk Road was the world's first commercial highway

between east and west,

the Amazon and eBay of the ancient world.

It wasn't a singular path

but an interconnected network that has been explored

by millions of intrepid travellers over the past 2,000 years.

The most important trading post in China was here in Xi'an.

I'm riding around the city walls, which is the first thing I've done

since I've got to China,

and, er, it's kind of mind-blowing, just, like, the scale of it.

Xi'an is a massive place by British standards.

And it's not even in the top ten largest cities in China.

In the late 13th century,

a European trader by the name of Marco Polo

recorded his impressions of the city, helping to cement his fame

as a legendary explorer.

He described Xi'an as a great plain filled with lakes,

round it a massive and lofty wall, all garnished with battlements.

What greeted him still greets me today -

26km of fortified walls.

What I notice about these walls is that they're very, very thick.

Just this section here is about 30m long

and that, I guess, would have been because the citizens of Xi'an

would have been very, very keen to protect all their goods,

which would have been inside the city.

For centuries, the focal point of the city was Xi'an's market,

with goods both coming in and going out along the Silk Road.

This is where the traders would have come

to sell their stuff, and also to buy stuff

that they were gonna take with them back towards the West.

I'm gonna be going on that journey,

so I'm gonna try and buy some supplies.

And I think you can get, kind of, anything here,

so we'll see what we're gonna find.

I'd like to think that at least some of the people across the years

who were heading off from this market into the unknown

might have been as nervous about the journey as I am now.

One of the things that virtually every traveller on the Silk Road

used to take with them

was some kind of medicinal supply,

and at the time it would have been mainly tea,

and here is a tea shop.

I could have Regulate Blood Pressure Tea,

if things get too exciting and I have to be calmed down,

or I could have Lychee Concubine tea which will keep off the concubines.

Is there any tea for headaches? Headaches? WOMAN: Jasmine.

Jasmine is good for headaches? Yes. OK, what about just to keep calm?

For skin?

No, I don't need skin, my skin's lovely. Aw.

Calm. Zz-zz-zz. Help sleep. Ah, sleep?

Help sleep, yeah. Oolong.

Oolong. OK. Oolong.

(SPEAKS IN MANDARIN) Thank you, thank you very much.

Now for the rest of my supplies.

I need a hat.

Aren't we going to some places where the sun's gonna be really hot?

Hm, it's a tough one, isn't it? All right, I'll have this one. Thank you.

I think just puffing away while I give you my thoughts on the Silk Road,

that might be quite useful as well.

How much is that?

Five?

OK. I think that is definitely useful to show the start of the Silk Road.

Obviously, it's in Chinese.

Last but not least,

like many travellers before me, I need a lucky charm.

(CROAKING RASP)

That sounds really quite a lot like a frog.

(CHARM CROAKS)

This is the one, this is the one.

In the midst of all these stalls

is a site that would have been hugely important

to many Silk Road traders...

(MONKS CHANTING)

..the great mosque of Xi'an. It's stood here for over 1,200 years.

One reason that quite a lot of the traders

would come here is they might offer up a prayer

before they set off on their long journey on the Silk Road.

Like most westerners,

I assume there isn't really much religion in China

because it was communist for a long time,

and its religion before that...

Confucius, a bit of Buddhism, whatever, but it turns out

that there's a powerful Islamic culture here.

So this is one of the central things

I'm starting to learn about the Silk Road.

With the movement of trade came the movement of culture,

ideas, religion.

OK, so, I've been given special permission

to actually go into the prayer hall.

Erm, and I'm gonna take my shoes off here.

For centuries, thousands of merchants would have done this very same thing

before they headed out west,

hoping that prayer would protect them on the road ahead.

They would be praying for health and be praying

for a prosperous journey, that their goods would be sold.

They might also, in this market, buy a lucky charm

in the hope that holding that with them

would also help their journey.

I'm a fundamentalist atheist, I'm afraid,

so I can't really offer up a prayer,

but I think I have got a lucky charm which might work.

(CROAKING)

So, I've been to the market and I've got all my supplies.

I've got my hat, I've got my tea, I've got my frog

and I'm gonna head out now on the road.

It's a long, long journey, the Silk Road.

It's 16,000km, and it begins here,

and I'm not entirely sure at the moment

where it ends, but I'm gonna find out.

I'm leaving the city -

which, obviously, being a Chinese city, takes a little while -

to unravel the secrets of the Silk Road.

I'm starting with the fabric that opened the world to trade.

I've been reading about the Silk Road.

The Romans were, like, addicted to silk.

They spent the equivalent of £65 billion on silk.

Most of it was worn by women and was regarded

as the ultimate status symbol.

But the production of silk was a mystery.

Despite being an incredibly forward-thinking empire

with a lot of ideas that still survive today,

they didn't know how to make silk.

And to be honest, I don't either.

But I'm travelling 250km

to a tiny peasant village in the mountains

in the hope that someone there can tell me.

This is quite exciting

because this is the first countryside we've seen since we've been in China.

It can feel very urban in China, but there's also this.

Somewhere out there in these fields

is the secret that we're looking for, the secret of silk.

I'm David Baddiel, and I've discovered that a lot more than just goods

travelled along the legendary Silk Road.

Religion and culture came, too.

I've left the eastern terminus, the city of Xi'an,

and am now headed out into the mountains

in search of the secret of silk.

For many years it was a state secret, the recipe for silk,

and you could be executed

if you gave that secret to a foreigner.

Erm, sounds harsh.

Now, of course, they just block Twitter and Facebook

but then...killed for silk.

Back then I'd have been risking my life pursuing this mystery.

So, I've arrived at a silk farm

and I think I'm gonna find out the secret of how silk is made

from this man.

Hello. I'm David.

OK. (LAUGHS)

Mr Zhu has been farming silk for over 30 years

with the help of a horde of tiny creatures.

And these are...these are worms. Oh, yeah, they are.

When you first see them, they look like tiny Twiglets.

Make me sort of peckish.

They're eating leaves. What sort of leaves are these?

(SPEAKS IN MANDARIN)

Can I pick out a mulberry leaf with silkworms on it?

(SPEAKS MANDARIN) Thank you.

Oh, my goodness. Quite a lot of silkworms,

and they're all a bit worried about this thing I'm doing.

I'll put that back. I don't want to create trouble in silkworm land.

A bumper silk crop depends on feeding the worms

their favourite food.

Luckily enough, Mr Zhu has a whole mountainside full.

We're going up here?

The Romans believed that the Chinese combed silk from forest trees.

Little did they realise it actually involves a very greedy worm

eating thousands of mulberry leaves.

This looks like a good one.

Just perfect. I feel the silkworms will really like this one.

I thought mulberry had a fruit as well, called the mulberry.

Where is that? Oh, there it is.

It's an important part of this process

that the mulberry-leaf pickers occasionally get to eat the mulberries.

That's definitely true.

I've read it in a book, a Chinese book.

Hm.

Very nice.

I don't know what the silkworms are thinking of eating the leaves.

The mulberries are fantastic.

I could revolutionise silkworm production

if I fed them berries, I tell you.

If you fed them the berries, they'd be enormous and fat

and the silk cocoons would already be kind of purple.

It would cut out whole processing.

But Mr Zhu's family doesn't just grow mulberries.

Hello. (SPEAKS IN MANDARIN)

Do you work in these fields?

(SPEAKING MANDARIN)

And what are you smoking there? (SPEAKS IN MANDARIN)

(SPEAKING MANDARIN)

(BOTH LAUGH)

I don't know what it is but it's making me laugh.

It turns out that another Mr Zhu grows his own tobacco next door.

(SPEAKING MANDARIN)

WOMAN: He is the brother of this gentleman.

Oh, he's the farmer's brother?

Yeah. Oh, OK.

Silkworms, they won't just eat leaves straight off the tree.

It has to be prepared so the silkworms will like it more.

Dinner, everyone.

Well, they really go for the mulberry.

They love it.

At what point does the worm

start doing something which can be transformed into silk?

(SPEAKING MANDARIN)

Mr Zhu tells me

that that's when they start to spin a cocoon.

This is the incredible secret of silk.

It's made from a trail of silkworm saliva.

The saliva solidifies when it hits the air and becomes a filament

that the worm spins around itself to create a cocoon.

But it's a thankless task.

The worms never go on to hatch into silk moths.

In mass production, the cocoons are boiled in water,

which kills the worm,

and the filament is unravelled, ready for spinning.

Over 6,000 silkworms are required

to produce just one kilogram of raw silk.

It is an incredible thing that those tiny little worms

are at the heart of this extraordinary industry.

I kind of knew that silk came from a worm, because I knew there was a thing called a silkworm,

but I don't think whenever I've worn silk

I've ever thought that it's actually, at the end of the day, a worm's house

that you're wearing or sleeping on.

I think it's OK.

We're about to leave, and I did quite a hard couple of hours' work

picking mulberry leaves and so I think I should be paid.

So I was wondering if this gentleman here

might pay me in tobacco.

(SPEAKING MANDARIN) Yeah, yeah, just in a tiny bit of tobacco,

yeah, of your homemade tobacco. Oh, there it is.

(BOTH LAUGH)

Yes, perfect. Thank you.

(CHUCKLES) Thank you.

I've got a tiny, tiny, tiny bit of tobacco.

It's raining so I've got to cover it.

OK, thank you very much, sir.

(CHUCKLES)

So I've got to say goodbye to Mr Zhu, and sadly I don't speak Chinese,

but luckily we both speak the universal language of the selfie.

(SHUTTER CLICKS)

Armed with the once-deadly secret of making silk,

I'm back on the road -

or rather, up in the clouds.

One advantage I have on my predecessors on this journey

is the invention of air travel.

My next destination is just over 1,500km away from Xi'an,

a major trading post on the ancient Silk Road,

the desert town of Dunhuang.

It's clear that we're at the point

at which the Silk Road becomes the desert road.

One thing that's becoming clearer and clearer to me

is that with the movement of goods and trade

you also have the movement of ideas and culture,

and coming to China, there was music, there was dance, there was religion,

there was art,

but we're going now, I think, to the most important

and most significant thing

that came to China because of the Silk Road.

I'm biased, but I've always assumed

that football was an English invention,

but since arriving here I've heard rumours of an ancient game

called Xuju or Cuju,

which literally means "kick ball".

Could China actually be the home of football?

Because that could be embarrassing.

Clearly, the honour of the beautiful game is at stake,

so I'm prepared to put my life on the line.

So I'm gonna play football

with a group of Chinese 14-year-old boys.

Er, this is obviously a mistake.

Hello, hello, hello. Nice to meet you, coach.

Hello, OK, so, this team is Man United...

ALL: Yes. ..and this team is Real Madrid?

ALL: Yes. OK, so I'm with Real Madrid.

(ALL CHEERING) Yeah!

We're gonna be playing a diamond shape

with just a little bit of movement

from the back up to the front. Keep it going, want the ball,

move into space.

Brilliant. (CHEERING)

Now, I do play football regularly, but I'm more used to taking on teams

that are my own age.

This might hurt a bit.

I don't know what the insurance is like if I have dehydration and a heart attack

and a broken back at the same time.

Come on, tackle, just make it hard.

Tackle! Well played.

It might seem as though they're running rings around my team,

but as we know, in football everything can change in a moment.

And again!

(GRUNTING)

Oh, yes! (LAUGHS)

And there you have it.

The goal that saved the face of English football in China.

Let's see it one more time. Just for me.

(GRUNTS)

Oh, yes!

Well played. Well played. Thanks.

Remember the name, Beckham. Thank you very much.

I can't reach it. I can't reach it. Ah!

(LAUGHING)

But amidst the heady celebrations,

there's still a very serious matter to be resolved.

Is the ancient game known as Cuju actually an early form of football?

Can I ask you something? Do you know what Cuju is?

Oh, yes, yes, from China, from China.

And is it like football?

Yes, yes. What's the differences?

(SPEAKING MANDARIN)

So it's exactly the same, just five a side?

In fact, Cuju had been played for centuries

in parks and palaces in Xi'an.

Just as ideas and culture came into China,

they also headed out west along the Silk Road,

and it's highly likely that would have included

the incredibly popular game of Cuju.

It came from the 10th century, when the nearest thing we had to football, I believe,

was just kicking a goat's head

between the only two villages not made out of mud.

I think I'm gonna have to concede a goal to the Chinese on this one.

Thank you.

As I leave there's one other Silk Road invention

that I'd like to try out.

In the 17th century, merchants were using trade cards

to act as sort of mini-adverts for themselves

and their goods along the route.

Erm, oh, you've already got one. Holding.

These have evolved into the modern-day business card.

There you go. You're supposed to give it with two hands.

Thank you.

I'm very much hoping that in 30 years' time I come back,

and all these people will be calling me up saying,

'I need a comedian, writer and presenter. Are you not around?'

MAN: Thank you.

I love football, wherever it was invented.

But I'm about to leave the familiar turf behind

and get a real taste of adventure on the Silk Road.

I can only hope they aren't the graves

of people who have tried to cross the desert by camel.

I'm David Baddiel, and I'm in China

on the trail of the ancient Silk Road.

I've learnt the secret of silk that had the Romans stumped...

It's actually a worm's house that you're wearing.

..and discovered that the Chinese invented football

over a thousand years before the British.

Oh! Yes!

(LAUGHS)

Where we're going now,

I think we'll be able to see what it was like

for the first travellers along the Silk Road,

because it's been called, this place, a time capsule of the Silk Road.

We're heading 25km southeast of Dunhuang,

home to one of the greatest archaeological discoveries

of the 20th century, the Mogao Caves.

There are nearly 500 caves

carved out of the rock and dating back to the 4th century.

They were created by Buddhist monks as a place of worship.

I've been granted exclusive access

to the ongoing project to preserve them

with my guide Miss Shuxia.

Hello. Nice to meet you.

This way, please.

Known as 'the caves of a thousand Buddhas',

they house one of the most valuable collections

of Buddhist art in the world...

Wow!

..including the second largest stone Buddha on the planet.

Where did all the materials come from?

The paints and the pigments?

Some blue pigments, like that one,

come from lapis lazuli from Afghanistan.

So they would have talked about using blue

and then, along the Silk Road, get the lapis lazuli from Afghanistan

in order to create the pigment to paint this.

Yes, yes.

These paintings are a first-hand visual record

of the culture and ideas that travelled along the Silk Road.

The music instrument here, like this lute, come from ancient Persia.

Comes from Persia? Yeah.

So these would have come along the Silk Road, these instruments?

Is this person playing the lute...

This is very famous. ..in the back of their head? Yes.

Like Jimi Hendrix? Yes.

So this is something that happened in China in the 10th century

and we didn't really get it in the West until 1968.

But just as we've begun to explore

this treasure trove of Silk Road secrets,

I discover it's under threat.

I notice there's a lot of work going on here,

presumably to preserve this? Yes.

The centuries-old delicate records are at risk of destruction.

The team is racing against time

to create a giant digital archive of the paintings.

It may look ancient, but this hyper-spectral camera

detects colours unseen by humans

so they can be accurately restored by hand.

As the team's technical director Su Bomin explains,

the artworks' biggest threat is blowing in from the desert.

Soluble salts in the plaster absorb moisture from the air,

causing the paints to flake.

To remove the salts,

the restorers dab the walls with absorbent sponges,

then inject an earth-based slurry to reattach the painted plaster.

So the cracks will improve and heal

because of that material being injected?

Yeah. It looks incredibly skilled and delicate. Yes.

More caves are being preserved every year.

They reveal not only the people who lived here

but those who travelled across continents to trade with them.

You can see the merchants, actually...

These? ..is western people.

They have high nose... Yes, they're not Chinese.

..and beard, yeah. Yes. Not Chinese face.

Yeah. But these bandits

actually wear Chinese clothes. The bandits are Chinese.

Oh, OK, so the Chinese are the bad guys in this situation?

Art like this demonstrates that there's a strong awareness

that travelling a long way along the Silk Road is full of dangers.

Yes. Ancient Silk Road, you know, is a very hard journey.

The caves are really amazing.

There's the most astonishing treasure trove of art here

and hundreds of caves that we haven't even seen.

What you get from the wall paintings

is representations of ordinary life as it's lived along the Silk Road,

and then you also get a sense of the fear and neurosis

inspired by travelling along the Silk Road,

because it's a long way to go and, you know,

there's a lot of potential bandits and potential assaults

and people who might just want to take all your goods away.

But bandits weren't the only threat.

Silk Road travellers had to brave

a 1,000km journey across the Taklamakan Desert,

and that's where I'm heading next.

One thing that does worry me a bit is the name Taklamakan,

which means, 'If you go in, don't expect to come out.'

So I'm putting my life

in the competent hands of camel guide Mr Li.

Hello, Mr Li.

Here is his camel caravan, and the thing is

a camel is the best way to get across this desert,

because a camel can carry 270 kilos

of whatever goods you want to put on its back,

it can walk for 40km in one day

and it can withstand temperature changes of up to 70C.

Here we go. Whoa, sorry!

Oh.

I'm on.

Do they...do they stand up? Hello?

Whoa. Oh, oh, oh, oh.

Eh.

We're up.

(CHUCKLES) Bit unexpected.

We set off on our desert trek

on a caravan consisting of six two-humped Bactrian camels.

700 years ago, 13th-century explorer Marco Polo did this very same trip.

His legendary account is an invaluable record

of the dangers of crossing the desert.

'For this purpose, they load a number of stout asses and camels

with provisions and with their merchandise.

Should the former be consumed

before they have completed the passage,

they kill and eat the cattle of both kinds.'

Really? OK.

I'm really hoping not to have to eat the camel,

but this is a vast, inhospitable desert.

It would certainly be daunting

if we were trying to cross the entire desert like this,

and actually, if you look out here...

..there are things that at first glance I thought

were strange Star Wars houses, but actually they are graves,

and I can only hope they aren't the graves of people

who tried to cross the desert by camel.

(SINGING)

After a few hours, Mr Li decides it's time to camp for the night

in a sea of mountainous sand dunes.

Thank you, Mr Li.

Getting back on my feet, I decide to stretch my legs,

which, on this terrain, turns out to be a huge error.

I'm told that at the top of these sand dunes, here,

is the best ever sunset view across the desert. (PANTING)

I actually will be dead before I get there,

but apparently it will still look great.

Am I actually going forward at all?

What you see here

are the strange sliding tracks of the slightly middle-aged desert Jew.

Where's my (BLEEP) camel when I need him?

Maybe I can use the sandals like crampons.

Hold on, here I go, sandals like crampons.

Oh, yeah! Chris Bonington, eat your heart out.

(PANTING)

It's very beautiful and, er, I might be hallucinating

due to my heart beating at 7,000 beats a minute but...

..sand, it's like silk, isn't it?

When it's like this, brushed...

..almost styled, it's like silk,

which would have at least impelled all those traders on...

..thinking that they were going to sell barrel-loads of it.

As night falls, everything becomes even more surreal.

So, I'm here in the middle of the desert camping

and the first important thing to do

is, er, smoke the tobacco

of that old brother guy who was at the silkworm farm.

It's fairly disgusting.

Marco Polo was convinced that this desert was haunted,

and I'm beginning to understand why.

'It is asserted as a well-known fact

that this desert is the abode of many evil spirits.

If any person remains behind on the road,

they unexpectedly hear themselves called to

by these spirits of the desert.

They're led away from the direct road and are left to perish.'

Actually, he's right, Marco.

There's a very weird bell-like noise that you hear.

(WIND HOWLING)

It's the sand, I believe,

but it is quite frightening,

and so I have to turn to the one thing I have

to get me through this danger.

(CHARM CROAKS)

(CAMEL GRUNTING)

Hello.

Well, that was a...

..fine night in a tent. Erm...

I wasn't drawn out into the dangers and uncertainties of the desert

by the whispering siren song of the sand...

..because I took a sleeping pill and got zonked out.

You see, that's what Marco Polo didn't realise.

It's simpler if you do that.

(EXCLAIMS)

OK.

(CAMEL FARTS)

That noise you heard was the camel farting, not me.

Yeah, less nuzzling from you today, please.

I can't imagine how tough it must have been

to do this for a month like old Mr Polo.

I've been in the saddle for less than two days

and the charm is wearing thin.

It's time to take my leave of the caravan -

not before observing tradition, of course.

Thank you. (EXCLAIMS)

Xie xie.

Thank you.

And thanks for the singing. Yeah.

Please yourself.

But Marco Polo isn't the only European

to crack the secrets of China.

I've been reading up on another explorer,

Sir Marc Aurel Stein, who was knighted in 1912

for his discoveries along the Silk Road.

A Hungarian by birth, Stein was the original Indiana Jones,

leading adventures in archaeology

across some of the most inhospitable terrain on Earth.

He travelled across China and most of Asia

uncovering and discovering all sorts of old relics.

Here is a picture taken by Aurel Stein in the early 1900s.

This is the Great Wall of China.

There's a reason you might not recognise it.

The Great Wall of China as you and I know it

is a 1950s renovation on the old foundations,

some say to raise China's national spirits

after the Second World War.

The original, built to defend China from invaders,

was made up of lots of different sections along its outer borders.

Aurel Stein recorded some of them onto maps.

There are bits and pieces,

if you follow this map of the Great Wall

where Aurel Stein says they are,

which we might be able to find if we're lucky,

but we don't know exactly where it is

so we've got to keep our eyes peeled for it.

I'm David Baddiel,

and I'm on an adventure through China.

I've discovered thousand-year-old secrets

locked away by past travellers.

And I've walked in the footsteps of Marco Polo

as he trekked across a haunted desert.

Today I'm 1,500km along the Silk Road

channelling Indiana Jones.

I'm in search of the original Great Wall of China

in the heart of the Taklamakan Desert.

That looks a bit like this, over there.

I just can't work out, to be honest, if it's Great Wall

or if it's termites,

but it looks pretty Great Wall-y to me.

I think we should pull over if we can and go and see if we can have a look.

Explorer Marc Aurel Stein was last here in 1907,

on his second expedition to China.

It's exciting.

His map refers to a ruined 19th-century village

called Shih-pan-tung. But what I'm really keen to find

is one of these features marked in red,

which are ancient watchtowers.

We've driven as close as we can to the point marked on the map.

From here on in, we're on foot.

The original Great Wall protected traders along the Silk Road

who were at risk of attack from nomadic warriors.

What we really need is a sign that just says,

'Barbarian hordes from the north. Keep out.'

If we find that, it's done.

As the threat lessened, the Wall was gradually abandoned.

OK, so, if I was an archaeologist - and remember, I'm not -

I would say that these bits here

do look to me like they are wall-like.

And there's also something interesting up ahead.

Could this be the ruined village Stein had marked on his map?

Yeah, there's definitely a man-built structure

as part of this, cos it's someone's house there.

(DOG BARKING)

Oh, whoa.

(BARKS)

Whoa.

(BARKING CONTINUES)

That was a mistake.

Are they coming this way?

OK, so, what's happened here

is that we were going over to check out this bit

to see if this was possibly a bit of Great Wall, get some clues,

and, er, three wild dogs have appeared to chase us off.

Now, I've got to be honest with you,

Indiana Jones would have dealt with this, but I'm not.

(BARKING CONTINUES)

Having evaded attack by savage beasts,

it's back to the detective work.

I seriously think I've cracked it.

This is where my vocabulary really struggles,

but I'm gonna use the word 'underlay'.

Now, I think that's a word for carpets,

but if you look, there's these enormous, great cubes of mud brick...

..and then underneath it's slightly finer sections

on which it's sitting,

and that seems to run all the way along,

so this was done by men.

Er...

So I think it is the Great Wall. There we go. (CHUCKLES)

So I think I've found

what Aurel Stein, in his original map of the Great Wall, called Tower 24.

The whole experience makes me feel, at last, like a proper explorer.

So far, I've covered less than a fifth of the Silk Road

and I'm still well inside China.

From here, I am gonna go on an overnight train to Turpan,

er, which will arrive at 6:40.

This is the longest railway built by communist China,

stretching over 1,900km.

Construction started in 1952 under Chairman Mao,

and the route chosen was along the path of the ancient Silk Road.

I'm hopping on an overnight train

to travel 700km to the city of Turpan.

So, er, that was the night that was,

and whilst I was lying here

I had a blindfold, I had some earplugs,

er, I had numerous herbal sleeping pills,

but what I didn't have was any sleep

because the train shunts, like, every three minutes,

which is a bit like being shaken awake by a giant.

Morning. Morning. Hey.

And so I've arrived in Turpan,

once an important ancient Silk Road stopover...

..and the source of an extraordinary mystery.

Located in the middle of the driest of deserts,

the Turpan basin

is the second deepest geographical depression

in the world.

It can reach temperatures of 47C,

and sometimes there's not a single drop of rain

for ten months at a stretch.

And yet in the middle of this barren landscape

sits a fertile valley.

It's really green.

There's trees and grass sort of everywhere.

I'm not sure how it manages to be this green,

but I think we're gonna find out.

Turpan is full of abundant vineyards

and home to one of the Silk Road's most successful commodities...

..grapes, as local guide Achmad explains.

ACHMAD: This small basin with a 600,000 population

can supply more than 90% of the raisin for the whole country.

90%... Yes.

..of the raisin supply for China... ..comes from Turpan.

Raisins have become Turpan's biggest success story.

The grapes travelled along the Silk Road from the west,

all the way from Afghanistan.

But with such an inhospitable landscape,

where on earth does the water come from

to sustain this consistently successful harvest?

The water comes from at least 60 or 70km away,

from the mountains which is covered with ice and glaciers.

The solution to the mystery

lies with some incredible underground engineering,

which was first built over 1,000 years ago

when the Silk Road was at the height of its trading success.

Engineers dug vertical shafts

to allow them to excavate an underground tunnel called a karez

leading from the mountains into the valley below.

Gravity sent groundwater down from the mountains

to irrigate the Turpan basin.

Today this ancient system

still provides a water source for Turpan and its thirsty vineyards.

Is there a whole network of them across this area?

Yes. How many?

Almost 1,000 just for whole Turpan basin.

One thousand? But now around 100 of them still running.

The ones that are still running are still irrigating this land?

Yes, it's... It's watering.

Achmad and his historian friend Mr Wuper

take me for an exclusive close-up view of one of the shafts.

The first well of the karez is the deepest one

and they are getting less and less deep.

How deep is this one? It's about between 60 to 70m deep.

Oh. (SPEAKS OWN LANGUAGE)

Whoa, whoa, whoa, whoa, that's deep.

OK, OK, thank you. (LAUGHS)

That's good, you were strong.

The karez was an extraordinary invention,

enabling viticulture and irrigation in the most unlikely of locations.

Just another of the amazing discoveries I'm making

along the Silk Road.

I'm just a quarter of the way into my journey,

but already I've learnt so much from the travellers

that have gone before me...

..from Marco Polo's detailed journals...

..to Sir Marc Aurel Stein's exciting discoveries...

..and from a tiny, greedy worm

to a huge, awe-inspiring Buddha.

Wow.

It's clear to me that the Silk Road paved the way

not only geographically but historically and culturally,

transporting us across the centuries to the world as we know it today.

Next time, I'm in the wild heart of the Silk Road,

Central Asia,

discovering the secrets of survival in this unforgiving land.

I was born to this.

Dive to find treasure in a sunken castle

and uncover what persuaded the Chinese

to part with their precious silk.

Are you telling me that's what the Chinese wanted?

subtitles by Deluxe