Original subtitles

This time I'm in the Caucasus,

a vital crossroads on the Silk Road...

It's a slightly nerve-wracking climb.

..risking life and limb on the hunt for one of its deadliest weapons...

That's an enormous dog.

..discovering hidden cities beneath bloody battlefields...

(EXCLAIMS) Wow.

..and uncovering the secret

that destroyed the greatest trade route in human history.

That's a lot of pigeon poo.

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

Whoa! (LAUGHS)

..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.

(ALL CHEER)

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.

Whoa, whoa, whoa. (DOG BARKS)

We have got a bit of a situation.

There've 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.

I'm in Georgia,

which has been described by historians as the edge of empires.

China is about 8,000km back that way.

That's where it all began, and now

2,000km that way lies home.

Well, not North London, but Europe,

Istanbul, and the end of the Silk Road.

The Silk Road's network of interconnected routes

snaked through the wilds of Central Asia...

..but its success attracted the attention of two giant empires,

who vied for its control...

..the Roman in the west, and the Persian in the east...

..and in the middle was Georgia.

One of the things about Georgia is throughout its history,

it's been invaded.

Georgia, in order to protect its trade,

built a lot of fortified castles, and that's one of them there...

..and now I'm gonna try and climb up to the top of that.

This is Khornabuji Castle.

It's just one of over 500 fortresses built in this region.

OK, this bit's a bit tricky.

The castle was a crucial link in Georgia's defences

against the Roman and Persian superpowers

as they battled to control trade in the 7th century.

To find out why it was so important, I need to get to the top.

It's a slightly nerve-wracking climb, but the view does make it worth it.

The castle's strength didn't come from its walls,

but rather its sky-scraping position.

I made it.

Not the easiest thing I've ever done in my life...

..but this, this was the land bridge

between East and West.

Towering an incredible half a kilometre over surrounding lowlands,

the castle's watchmen could see for 40km

along the disputed stretch of the Silk Road.

They could spot an attacking army a day's march off -

plenty of time to organise defences.

That's why it was so valuable...

..why it was so fought after.

Prime strategic locations made castles like these

highly sought-after prizes

in the battle for Georgia and the Silk Road...

..but it wasn't just the vantage point

the invading Persian and Roman armies wanted.

These fertile plains of the battlefield held a secret.

Trade along the Silk Road, of course, is all about imports and exports,

and Georgia had a particular export that it was keen to protect.

I'm gonna go and have a look at that now,

and I'm looking forward to seeing this particular export

because I need a drink.

Long before even Silk Road times,

the rich soils of this vital land bridge proved ideal

for making a highly-prized commodity,

wine.

American John Wurdeman married into a Georgian family

and bought this ancient vineyard in 2007.

He's continuing the old wine-making tradition

in the land where it all began.

John, since I've been in Georgia, I've seen a slogan a couple of times.

It says, 'Georgia, the cradle of wine.' Right.

Is that true? Was wine born here?

There's been ancient evidence of wine-making in Mesopotamia,

in Egypt, in Iran, but nothing so old.

There's been an unbroken tradition

for over 6,000 years of making wine in Georgia.

It was here in these plains

that wild grapes were first domesticated into a crop...

..and not only that, soon after, the Georgians invented the technique

of fermenting grapes into wine.

The Silk Road carried these skills east, reaching as far as China,

but in the birthplace of wine, the battle for trade raged on.

Right now, the vineyard we're in, it was a battlefield.

Georgians believe that the best fertiliser for a vineyard

was the blood, sweat, prayers,

and remains of their ancestors that fought to keep this country whole,

and that all of the invading, the Persians, the Arabs, the Mongols,

are contributing to the vineyard.

Using the battlefield's fertile soils,

John is recreating the wines of the old Silk Road.

Here, we don't make wine, we raise wine,

just like we raise our children.

Give birth to wine. Yes.

Well, the earth gives birth and we're just custodians...

I see, you're the midwives.

John's invited me into the construction of his new cellar

to reveal how the first wines were made.

This is how they sit in the earth? Yeah, this is how they sit,

and this will be the floor of the winery over here.

The wine is made in giant clay pots called kvevri.

They're buried up to their necks in the ground

before crushed grapes are poured inside.

The pot is then covered and left to ferment and mature.

So, here's a wine-maker.

The opening of a kvevri is a big deal in Georgia...

(SPEAKS LOCAL LANGUAGE)

..and John has given me the great privilege of taking part today.

John filled this kvevri eight years ago.

None of us know what state the wine is in now.

Oh, my God. Yeah, it's really full.

Look at that, that's eight years it's been in there.

Hopefully, it's not the world's biggest bottle of vinegar.

(SPEAKS LOCAL LANGUAGE)

It's fantastic.

Yeah, it's incredible.

Like so many Silk Road wine merchants before them,

John and his team are understandably relieved.

It is fantastic. Tastes absolutely fantastic.

Delicious.

Before I leave the birthplace of wine,

John has invited me to a very special celebration

that traces its origins back to the times of the Silk Road.

This is a supra.

Literally meaning 'tablecloth',

it's a village gathering held to toast travellers,

and would have been a highlight for many a weary trader arriving into town.

Wow. Look at this. Amazing.

The most important person is the toastmaster.

The first toast I'd like to drink for being grateful.

It's customary for a supra to have 20 or more toasts.

For friendship.

For peace. Peace.

May our families be strong.

For love.

It's said that the average Georgian

will spend several hours a week attending these feasts.

Sometimes the big ones go on for days.

I'm beginning to worry that my carefully-planned schedule

along the Silk Road may have hit a delay.

After several toasts and glasses of wine,

I'm ready to join in with the supra tradition.

There is something that has brought me here and which, in fact,

has brought the wines of Georgia to and from here and all over the world,

and it is the reason that I'm here, and it is the Silk Road,

and so I thought perhaps we should celebrate it

because it's the reason why we're all here.

So I give you the Silk Road.

The Silk Road. (TOASTS IN LOCAL LANGUAGE)

But wine isn't the only thing Georgia exported along the Silk Road.

(ALL SINGING)

As Christianity spread along the trade route,

this Georgian style of singing, called polyphony,

was assimilated into its ceremonies,

and it's believed this is how Christian hymns may have originated.

Amazing.

Let's wish David happy, healthy journeys,

full of adventure and spice.

Onwards and forwards. Thank you.

Great journeys. Thank you very much.

(ALL TOASTING)

I hope I won't regret the merriment, because tomorrow

I'm going to be heading off-road

on the trail of yet more Silk Road secrets.

I'm David Baddiel, and I'm in Georgia.

So far, I've discovered that this ancient battlefield

was the birthplace of one of the Silk Road's greatest exports,

wine.

Right now, the vineyard we're in, it was a battlefield.

Now my long journey west takes me through the Caucasus Mountains.

Since we've come up into the mountains

it's started raining quite heavily. There've been reports of landslides,

rock falls and mud avalanches and stuff,

so the actual pass across the mountains may be blocked.

I don't know, but we're gonna give it a go anyway.

Back in Silk Road times,

traders needed to avoid the warring Roman and Persian empires...

..so if they wanted to reach Europe and its markets,

it meant having to take their chances

in the treacherous mountain terrain...

..and that's where I'm heading now.

This route through the mountains may have been used for centuries,

but that hasn't dulled its danger.

This is the Silk Road at its least silky.

I think one has to ask, philosophically,

when is a road no longer a road?

And I think we may have reached that point now.

(CAR HONKS)

In the past 12 months alone,

eight people have been killed here in landslides...

..but hopefully that's not gonna stop me in the search

for my next Silk Road revelation.

One of the things that was very important along the Silk Road

and was actually a very valuable commodity

was dogs, it turns out,

because you needed something to protect yourself with

along the Silk Road,

and dogs were very useful for protection

both against thieves and against wolves and bears,

and there was actually a particular dog

that came from this area called the Alaunt,

which was the great war dog of the nomadic tribes.

'He attacks by running at the intruder and knocking them to the floor

before attacking them when they are down.' OK?

'And he knows where the most vulnerable part of the victim's body is,

and will aim for there.'

Although the ancient Alaunt is extinct,

I've heard their descendants can still be found in remote farms

that depend on their protective instincts,

but with Mother Nature against us, the chances of finding one look slim.

I'm, sort of, 85% certain that we're either going to get stuck...

..mauled by a dog or a bear, or just fall off the edge and die,

but it is almost worth it for the incredible landscape

in this part of Georgia.

But then, after hours of searching,

my local guide Nick assures me he can hear something in a nearby farm.

(DOG BARKING)

I mentally wave goodbye to my vulnerable parts.

(CHUCKLES) I'm terrified.

OK, that's an enormous dog.

Hello.

Is it chained up? MAN: Yeah.

Hello. Erm...

Can I ask you about your dog?

Is it a Caucasus shepherd?

(SPEAKS OWN LANGUAGE)

Yeah, it's a pure Caucasian shepherd, yeah.

It looks very dangerous. Is it...?

What do you use the dog for?

These dogs can weigh an amazing 90kg...

..and it looks to me like they are the descendants

of the ancient war dogs

brought to battle by kings and emperors

fighting for control of the Silk Road,

and there's another one here.

That one is very, very aggressive. This one is more aggressive.

Oh, my God.

That is a terrifying dog.

Tell me, have you sold the puppies? Yes.

Where did you sell the puppies to? Kazakhstan.

Kazakhstan. Kazakhstan.

So the trading of these dogs still goes on along the Silk Road?

(TRANSLATES)

They may be perfect guard dogs,

but I'm glad to put some distance between us.

OK. All right.

Thank you very much, sir. Madloba. Thank you. Let's go.

After such a rough ride,

I could certainly do with an energy lift about now,

Silk Road-style,

and I've been told the mountains are home

to one of the earliest versions of confectionery.

Definitely that's gonna help.

These sweet treats, called Churchkhela,

are an ancient Silk Road ration that kept weary travellers fuelled,

and were considered the perfect use for Georgian grapes

that didn't make the grade for wine,

and I'm about to get a master class in how to make them

from traders Dalli and her daughter Dinara.

Grape juice with flour, boiled, and then you add walnuts.

It actually tastes not very sugary.

Can I have a go?

The high sugar content from the grape juice

gives the Churchkhela a shelf life of over six months,

ideal for long journeys along the Silk Road...

..and with an estimated 2,000 calories per piece,

they'd certainly keep you going.

Thank you. Thank you. Madloba, madloba.

Refuelled on Silk Road sweeties, my journey continues west,

past the Caucasus and onto the home stretch...

..but for travellers along the Silk Road,

things were not about to get any more peaceful.

Clear of the mountains of Georgia,

I follow the route into the firing line of a new emerging force,

Islamic tribes.

They wanted control of the Anatolia region, today Turkey,

the merging point of several branches of the Silk Road.

During the time of the Silk Road,

this was an absolutely vital trade intersection.

As a result, it had to find ways of protecting itself

from the various bandits and oppressors

who would essentially want to overrun it...

..but unlike some of the other places that I've been to,

the people here found a way of protecting themselves

and their merchandise that used the landscape.

This is Cappadocia, where strange cliffs,

the remains of volcanic eruptions,

stretch over an area three times the size of London.

The people here discovered the rock was soft and easy to carve,

so began cutting homes into the landscape...

..but it's what lies beneath these rocks that is the most extraordinary,

a giant network of 200 underground settlements.

I've gained access to one of the largest,

Kaymakli.

Guide Sevim Karabiyik is helping me discover

what life was like inside here.

This is like a labyrinth.

These were no mere subterranean apartment blocks.

Supplied with water, air, and well-stocked with food,

these giant bunkers were built for siege.

(EXCLAIMS)

Wow. This is incredible.

It's a ventilation shaft.

In times of danger, up to 5,000 local residents and traders

would escape underground.

So, they packed their permanent storage places here,

and they were living up there, coming down here to get their stuff

when they needed some food or something,

but when they were alarmed about the enemy approaching,

all they had to do was to grab their kit,

get down, block the entrances.

Kaymakli's residents could survive for six months without going outside.

Built around a series of ventilation shafts,

its network of 100 tunnels spanned eight floors

and connected 64 rooms...

..as its residents carved stables, wineries, kitchens,

and even churches into the siege-proof complex.

Key to survival was security,

and this included an ingenious Indiana Jones-style invention.

This millstone door here was carved in situ.

They carved this column here,

and the aim was to block the passage coming from the upper level.

Through the hole, people on this side could see

what was happening on the other side, could spear the enemy.

And taunting them as well, maybe? Yeah.

Even the narrow tunnels were designed

with the aim of defending the people from attackers.

Imagine you're the enemy trying to attack this place.

How would you handle that tunnel?

Badly. I handled it quite badly anyway and I'm not an enemy.

It starts to become very difficult to carry any kind of weapon.

Do you think you would be able to wear your armour? No.

And one person at a time. Yeah.

Those narrow, winding tunnels was a big part in their defence system.

I don't know if it's because of it being a siege situation,

but there appears to be no hierarchy,

there appears to be no bigger room for the king,

or no bigger room for the lord and smaller room for the servants,

which is what you would find in a castle, normally.

That's right. I've never thought about it. That is the case.

Kaymakli was first excavated and opened to the public in 1964.

Now, on the outskirts of the city of Nevsehir,

an exciting new underground city has Turkish archaeologists abuzz.

We've secured access as the first film crew

to join the archaeologists as they investigate this site.

It was discovered by construction workers in January 2013.

A team of experts are using cutting-edge technology

to assess just how important this find is.

So, what about this, what's happening here?

They're photographing the place and taking measures of the place, 3D.

In 3D?

These early renderings of the measurements suggest

that there could be as much as 7km of tunnels

going 37 storeys underground.

If true, this will make it the biggest underground city

ever discovered along the Silk Road.

Most of the tunnels are yet to be explored,

but I've been allowed into one that even the archaeologists themselves

have yet to examine.

So, there's a network of tunnels through here...

..and there seems to be a reluctance for anyone to actually go in here,

so I'm gonna go by myself.

Been nice working with you.

This is quite exciting because this room hasn't been

cleared yet by the archaeologists,

so I just came in here by myself, really.

The network carries on through here...

..and it's getting, I mean, genuinely Indiana Jones-ish here.

I don't want to meet the spider that produced those things.

Looks like you could catch a fish in them rather than a fly.

I'm no archaeologist, but these tunnels share features with others

I've been seeing in my explorations.

I reckon this is a burial chamber.

It's got a very developed arch, plus these stones here,

so I think this was potentially a burial chamber,

maybe for the enormous spider.

It will take the team years of painstaking work

to fully uncover this secret underworld.

Once it's done, this incredible city will be open

to all modern-day travellers along the Silk Road...

..but secret bunkers are not the only mysteries

that lurk beneath this fairytale landscape.

There was one that threatened to blow the whole Silk Road apart.

(BOOM)

I'm David Baddiel, deep in the alien underworld of Cappadocia in Turkey.

(EXCLAIMS)

Wow.

This is home to a network of underground cities

that protected over 100,000 people

from marauding tribes along the Silk Road...

Imagine you are the enemy. How would you handle that tunnel?

Badly. I handled it quite badly anyway, and I'm not an enemy.

..but yet more secrets to survival are hidden in these hills.

Yesterday it became clear to me

that living in Cappadocia meant that you were constantly under siege,

which is why they found ways of using the landscape

and burrowing into the rock to protect themselves,

but obviously, one of the things about being under siege for a long time

is you have to find ways to survive, ways to feed yourself,

and so I'm going now to find out

about the secrets of how they managed to do that.

While the volcanic landscape is ideal for building bunkers,

it's useless for cultivating crops...

..as local chemist Savas Kurkcu explains to me.

Salvation for food-growers came from an unlikely source.

For fertiliser? Fertilisers.

Yes, one of the most valuable resources

along the Silk Road was pigeon poo.

So valuable, in fact, that the locals carved the birds custom-built caves,

with some ingenious designs.

Every farmer painted his own unique design on his bird cave

to ensure his pigeons would find the right toilet.

Oh, is that right? Yeah, their own house.

These ancient ways are still used today,

and I've been invited to join local farmers Bekir and Hussain

to collect this precious cargo.

So, apparently I'm going up there

into a pigeon cave to collect pigeon poo.

I can't quite remember why I signed up to that.

Maybe I turned over two pages at once, I don't know.

If I can just show you that ladder, it's quite near the edge.

The entrances were deliberately kept high and very small

to keep predators like foxes and weasels from being able to get in.

There's quite a lot of these...

(SAVAS SPEAKING)

That's where the pigeons would nest?

So, how old is this, do we think?

But breathing in pigeon-poo dust can be dangerous.

OK, we're in a cave, we're putting masks on.

Let's be honest, we look like Al-Qaeda.

OK, so, there's quite a big pile of poo here.

Owing to the relatively small amount of fertiliser each bird produces,

back in Silk Road times, collections were made only once or twice a year,

and that's still the case today.

Whoa.

That's a lot of pigeon-poo smoke.

This is the sort of thing you might see in a middle-class household in a vase,

and he's just picked it from his garden

and uses it to brush up the pigeon poo,

as farmers have been doing for centuries.

With a bumper yield of fertiliser, our morning's work is done...

..but while pigeon poo was celebrated for its agricultural uses,

it also harboured a dark, destructive secret...

..that ultimately led to the downfall of the Silk Road.

All right, so the same thing that the soil decomposes the droppings into

can also be extracted... Chemically. ..for explosions? Yeah.

So, how did they turn pigeon poo into gunpowder's magical ingredient

potassium nitrate?

My pal Savas is helping me see if I can do it

with some kitchen-sink chemistry.

Oh, my God, it's a bit hot.

I think that's not very well balanced.

Do I put that in there? Yeah, yeah, you can. This water? Yeah.

One of the things it's very important not to do

is mistake it for muesli.

It's a Chinese discovery. Gunpowder was invented by the Chinese,

and presumably came here on the Silk Road.

Yeah, yeah, yeah, yeah. 11th, 12th, 13th century.

The Chinese first invented gunpowder in the 9th century.

They got most of their potassium nitrate from bat droppings...

..but like silk production, it was a closely-guarded secret,

until, that is, the Mongols invaded China and brought the secret west.

As traders returned home with the knowledge,

the question was, could they extract potassium nitrate

from their huge stocks of pigeon poo?

So, we filter that.

I'm beginning to worry our technique might be lacking some sophistication.

That doesn't look right.

Right, we've let it dry under the sun,

and you see the crystals are being formed.

Yeah, and those are crystals which are basically potassium nitrate.

That is the essential constituent of gunpowder? Exactly.

That drop is war.

But potassium nitrate alone isn't gunpowder.

You're gonna add some other ingredients to this

to make it into gunpowder, OK? Yes.

I should say at this point

we are not going to tell you viewers how to do that. We're going to do it,

but we're not gonna tell you the exact ingredients, cos we're not idiots

and we know there are some people out there who may use it for the wrong purposes.

It's a delicate job.

If you are trying to make gunpowder,

you want, definitely, one of these that sounds incredibly like a bell.

If I was the 12th-century police,

I would think, 'Where's that ringing? It's someone making gunpowder again.'

And it has a precise recipe.

Let's hope for the best. Yeah.

In the wrong hands, this could be deadly...

OK, here we go. Stand back.

Let's scoot.

..or just embarrassing.

Come on, let's go.

Looks like my O-Level Chemistry

isn't quite up there with the Silk Road experts...

..but trust me, with the secret to gunpowder now out,

warfare was transformed.

It had devastating consequences for the Silk Road.

Now I want to go in search of what happened next.

I love this area. It's one of my absolute favourite places along the Silk Road.

It's so astounding, I think, but I'm gonna have to move on,

and history moved on, too,

because despite it being the most fortified place along the Silk Road,

the place where the landscape absolutely allowed you to withstand siege,

Cappadocia did eventually fall. The Byzantine Empire

fell to the various marauding tribes that always tried to take this area.

Eventually it fell,

and in fact, that empire, the Byzantines, were pushed back

to their last stronghold, which was Constantinople,

and that now is called Istanbul.

Constantinople was the jewel in the Silk Road crown.

It was the end of the road,

and served as the transit point for goods arriving from the East

to be sold on to Western Europe,

and it's here, to this ancient gateway,

I've come to find out how the Silk Road met its end.

The wealth of Constantinople, today Istanbul, was legendary.

At its height, it was the biggest and wealthiest city in all of Europe.

Pickles.

To protect their bounty,

the city's Roman Byzantine rulers built over 22km of walls

to deter would-be attackers.

It seemed impossible that such heavy fortifications could be breached.

Last time I was walking around city walls this big and this thick,

I was in Xi'an, at the very start of the Silk Road.

Of course, the main difference between Xi'an and Istanbul

is that Xi'an was never taken by outside forces,

and so its city walls just remain pristine and fortified,

whereas these ones are in considerably worse nick.

The battered, crumbling walls of Constantinople

bear the scars of a fight.

I'm going to the famous Hagia Sophia to discover more about that fight.

Historian Ferudun Uzgamush has secured me a private visit

to what was, for 1,000 years, the biggest Christian church on Earth...

..and constantly under threat of attack.

The walls of Constantinople are withstanding attacks all the time.

Right, so it was quite a big incentive? Oh, yeah.

Inspired by this spiritual invitation,

on April 6, 1453,

Islamic soldiers of the Ottoman Empire launched an all-out attack

on the Roman forces...

..using giant stockpiles of a weapon they could now make,

gunpowder.

Their army smashed down the city walls

with the largest artillery barrage the world had ever experienced.

The victorious Sultan Mehmed II

entered the church and declared it was now a mosque.

Just explain to me what these big Islamic discs that are here...

The Roman Empire that had stood for 2,000 years

and created the Silk Road was destroyed for ever.

You're talking about a wholesale cultural transformation, aren't you?

And that's what happened, this is what this building represents,

as opposed to just, 'We want this place,

we want this building, we want this power.' It's bigger than that.

It's a wholesale spiritual, cultural transformation. Of course. True.

The Silk Road was under new management.

One of the things that is very interesting to me

is that this building was converted to a mosque

rather than being razed to the ground.

To raze the cathedral to the ground? No, no, no.

Is it? No, no, no.

It's very rare to be in a religious building

that's been so cross-fertilised. It's kind of strange, but amazing.

It's good to know that in the 15th century,

when the Muslims overtook this place,

they decided to keep some record of the previous religion,

even if they decided to whitewash over it,

because only... At least whitewashing over it

means you can eventually restore it.

For a while, trade flourished under the new Ottoman rulers,

but after years of stability, things were about to change again.

Next, I go in search of what was the death knell for the Silk Road.

It's ironic because, of course, the Silk Road begins in China,

and a Chinese invention destroys the Silk Road.

I'm David Baddiel, and I'm in Turkey.

I've discovered the remarkable secret ingredient of gunpowder...

That drop is war.

..and how that Silk Road invention

resulted in the fall of its greatest city.

You're talking about spiritual, cultural transformation.

Of course, sure, 100%.

So far, my journey has taken me over 10,000km

in the footsteps of traders and pioneers.

It ends here in the city of Istanbul -

back then, Constantinople.

As the traders came to the end of their journey they would, like me,

have been tired and dirty.

So I want to experience what is arguably

one of the greatest gifts the Ottomans gave

to those weary travellers,

the Hammam.

I'll be honest with you, if this wasn't on telly, I'd have taken the wrap off by now.

I'm lucky enough to get a private visit to this bathhouse,

built in 1556 by the sultan's personal architect.

It offered royal bathers relaxation...

Like being in the bath without being in the buff.

..and a good scrub-down.

Put your hands up, please.

So skilled.

These bathhouses proved so popular,

they caused a city-wide water shortage...

Your Highness.

..and the Sultan had to put a halt to building any more.

I can certainly see why the sultans loved them.

You're being intimately adored, which I think a sultan would have liked.

However, if I'd been in there ten more minutes in that steam room,

I'd have looked more like a sultana.

See what I did there?

Now as my own journey nears the finishing line,

I want to find out how the Silk Road finally met its end.

I'm heading into the seat of power of Sultan Mehmed II,

Topkapi Palace.

After the Sultan defeated the Romans and took control of Constantinople,

he ruled his Ottoman Empire from here.

Marios Hadjianastasis is an expert on its history.

This represents a huge empire that went on from 1300

all the way to 1922.

We've reached the point on the Silk Road journey at which

the Silk Road becomes taken over, essentially, by the Islamic world.

What are the consequences of that?

After the conquest of Constantinople,

they begin to have control of the trade routes

and therefore, the Europeans have to go through using a middleman.

So the Sultan and the Ottomans decided they wanted to control

this absolutely central part of the Silk Road,

and that made it difficult for the trade further on to Europe?

I think it made it less profitable. It made it less profitable. Yes.

But at the same time, what happens a little bit further to the east,

the big states, empires,

which control that route start falling apart.

As the Ottomans took control of the West,

war broke out in Central Asia,

and its kingdoms became hostile towards outsiders.

In the East, China grew distrustful of these warring neighbours

and closed its borders to foreign traders.

Suddenly, doing business along the Silk Road

became much more difficult.

So it's a combination of developments

which brings about the demise of that long haul route.

So, literally, the global market starts to become more complicated

for the people who have always controlled it? Absolutely, absolutely.

The Silk Road's days were numbered.

The final straw, like the silk which started it all,

was yet another Chinese invention

that travelled west along the trade route.

Today, it can be found in every ship on the planet,

and Marios is going to show me.

What happened is in the 8th century, the Chinese invented the compass

and it made it possible to navigate the world

without just relying on measuring the distance from the stars.

The compass allowed ships to safely navigate

around the coast of Africa...

..which meant that European traders could take to the seas

and cut out the middleman.

So, at a point in time when it's becoming

more and more difficult to travel by land,

traders decide, 'Let's move from land to sea.' Yes.

So there's a huge irony in the fact that

the compass was initially invented by the Chinese,

and the compass contributed greatly to the demise of the Silk Road.

Well, it's ironic because, of course, the Silk Road begins in China

and is powered by Chinese invention,

by gunpowder and paper and Chinese ideas coming down that road.

Shipping overtook transport by land,

and the Silk Road's dominance over the world economy was finished...

..and my journey has now ended.

There's just time to take one last look at this ancient gateway city

from the waters of the Bosporus.

It's been the most incredible journey,

and it's been a journey not just of kilometres for me -

it has been a journey of understanding.

If you've travelled, like I have, along the Silk Road,

the significance of this stretch of water becomes heightened.

You realise that that journey from Asia to Europe

was one that only began properly with the Silk Road,

which was the beginnings of the world talking to itself,

countries beginning to converse and beginning to share ideas,

and culture, and religion,

and with that came the modern world.

It's been an epic journey from East to West.

I've travelled 10,000km...

..across seven countries.

I've trekked deserts in the footsteps of Marco Polo...

And less nuzzling from you today, please.

..scaled mountaintops in search of the nomads who began it all...

Bye-bye.

Bye-bye.

..dived for treasures of lost kingdoms...

..to uncover the secrets of the road

that led to the world as we know it today.

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