At the beginning of recorded history, some time in the third millenium BC, one of the Indo-European or Indo-Aryan speaking peoples of these steppelands succeeded in domesticating the horse, revolutionizing warfare and transforming themselves almost overnight into a formidable fighting force. Wave after wave of horse nomads swept across Europe and western Asia, meeting resistance only from the sedentary civilizations of Mesopotamia and Egypt, which were able to withstand the assault only by adopting chariot warfare - if not mounted cavalry - themselves.

These nomads, speaking closely related languages and sharing a common social organization, were the ancestors of, among others, the Greeks, Romans, Persians, the Indo-Aryan speaking conquerors of India, and of many other lesser-known peoples who were later to play an important role in the history of the various segments of the Silk Roads.

Time and distance obscured the common geographical and linguistic origin of these widely scattered peoples, and it was not until the 19th century that the relationships among all their languages was fully worked out and their homeland in the Asian steppes identified. When Alexander fought Darius at Gaugamela, he had no notion that the Persians, at least linguistically, were cousins of the Greeks. The Greek and Roman historians who later chronicled his campaigns derived a great deal of dramatic play from the contrast between stern Macedonian virtue and the decadent luxury of the East, between Greek freedom and Persian slavery, between Europe and Asia. These attitudes penetrated deep into the European consciousness - they surface occasionally today - and erected a mental barrier at times almost as impassable as the Pamir Mountains that protected the farthest outposts of China from those the Chinese called "the western barbarians."

For the Chinese, like the Greeks - but perhaps with more reason - divided the world into civilized and barbarian. They, like their counterparts in India, Mesopotamia and Egypt, had had to face the fierce mounted bowmen of the steppes, and to survive had had to adopt their enemies' methods of warfare.

The pattern established in the second millennium BC - the settled, agriculturally-based urban civilizations of China, India and the Middle East regularly exposed to attack by mounted horsemen from Central Asia - did not end with the settling of the Indo-European speaking nomads. As they were transformed, as a result of the success of their own conquests, into urban civilized peoples themselves - Greeks, Romans, Persians and Indians - they in their turn had to defend themselves against new attacks by mounted horsemen from the Eurasian steppes - Parthians, Huns, Turks and finally Mongols. The last great wave of invasion out of Central Asia occurred in the early 15th century of our era, when Tamerlane and his Turkic- and Mongolian-speaking hordes devastated the Middle East.

It is no wonder that Ibn Khaldun, the 14th-century Arab philosopher of history, saw the history of the Middle East in terms of urban peoples periodically assaulted by mounted nomads, who then adopted the civilized ways of the peoples they conquered, became thereby decadent and in their turn submitted to a new wave of nomadic invaders. Had Chinese historians been able to read Ibn Khaldun, they would have found his paradigm borne out by their own experience.

No fully satisfactory explanation has ever been offered for the periodic explosion of nomadic peoples from - or through - Central Asia, but the pattern is clear: The region has historically been a sort of dynamo generating population movements that have affected Europe, Asia and America since the beginning of human occupation of the Eurasian landmass.

The Chinese fear of the peoples to the west was therefore not without foundation. In the third century BC the short-lived but powerful Qin Dynasty linked up a series of earlier bulwarks and formed the Great Wall, effectively separating the settled and cultivated lands of China from the nomadic herdsmen without. The Great Wall stretches from Gansu to Manchuria, a distance of 2,400 kilometers (1,500 miles). It was an effective defence against nomads who lacked both siege machinery and the inclination for sustained warfare.

It was not, however, impermeable. By the time of the subsequent Han Dynasty in the second century BC, the Chinese were regularly trading silk and grain for horses and jade with the western barbarians - horses which they employed to withstand the attacks of those same barbarians. Some of this silk, passed from hand to hand, found its way into Greek and Indian hands for perhaps the first time. Northern nomads had been familiar with it for hundreds of years, but now it began to filter into the markets of the large urban centers of western Asia. Significantly, our word China, like the Persian and Greek names for the country, comes from Qin (pronounced chin), the name of the dynasty that first united China and built the Great Wall.

The energetic and commercially minded Greeks established trading colonies on the coast of Asia Minor very early, and the wealth accumulated in them has become proverbial - "rich as Croesus," we say, naming the king of Lydia, in present-day Turkey. These Greek colonies had been tolerated by the Persians, but during the fifth century BC the two expanding powers came into conflict. Darius, from his capital at Susa in southern Persia, had waged a successful war against the Medes and their Babylonian allies, and succeeded in taking the Medean capital of Ecbatana - Hamadan, in present-day Iran - and forming a great empire stretching from the Oxus to the Tigris. His ambitions extended to Anatolia, and he succeeded in taking Sardis, the Lydian capital, and subjugating the Greek colonies on the coast. He then attacked Macedonia and Greece itself, and was only stopped by the heroic Athenians at Marathon, in 490 BC. His son Xerxes won the battle of Thermopylae and razed Athens, only to be defeated in the famous naval battle at Salamis and driven out of Greece.

These events, which loom so large in Greek and European history, had two consequences that were to change the face of Asia. One was administrative: Darius established a system of roads linking major Persian cities with the Mediterranean coast, and this Royal Road, leading from Susa to Sardis, was to become the main trade route – and the preferred line of march - across the Anatolian Plateau to the wealthy cities of Mesopotamia and beyond. The road was garrisoned and supplied with caravanserais, with amenities for travelers, at regular intervals. The world was suddenly a smaller place, and the enormous extent of the Persian Empire - at its height it included all of the Middle East and Egypt - meant that markets and producers that had formerly been separated by hostile powers were now united under a single rule.

But the other consequence of the Persian attack on Greece was a bitter hatred of Greek for Persian, and this was what in the end destroyed the empire so carefully constructed by Cyrus, Xerxes and Darius. In 334 BC Alexander of Macedon, 23 years old, landed on the Anatolian coast, intent on avenging the Persian attack.

At the head an army of 10,000 men, Alexander defeated Darius II, Great King of the Persians, first at Issus, in 333 BC, and then, crushingly, at Gaugamela, "The Place of the Camels," two years later. In the interval between the two battles, Alexander captured Tyre, Sidon and Gaza, conquered Egypt and founded Alexandria, destined to become perhaps the greatest intellectual and commercial center of all time. After Gaugamela, Alexander marched on Babylon, Susa, Persepolis (which he burned to the ground) and Ecbatana. He extended his sway beyond the Oxus, founding a city on the Jaxartes River, and taking Bactria, in modern Afhanistan, and Sogdiana, in what is now the Uzbek Soviet Socialist Republic - two places that for centuries thereafter would play an important role in the trade with China.

Alexander's lightning attack on India, his return march through the desert to Susa and Babylon and his sudden death are the stuff of legend, and his conquest of the mighty Persian empire with so few men - perhaps no more than 80,000 at the most - left an indelible impression on the literature and art of the East.

The frontiers of Europe had been extended to the Ganges, and the effects are almost incalculable. The Greeks were exposed to very ancient and civilized societies, with their own customs, languages, literatures, dress and luxuries. By a happy coincidence, Alexander's conquests took place at a time when Greek art and thought were in fullest flower, and the peoples of Asia were quick to adopt - and adapt – the esthetics of Greece. The results were astonishing, and a single example speaks volumes: a carved stone head of Buddha whose style is Greek and whose features are recognizably those of the idealized Alexander of Greek sculpture.

On Alexander's death, the conquered territories were divided among his successors, Seleucus and Ptolemy. Seleucus took the lion's share, ruling over most of Anatolia, Syria, Mesopotamia, Persia and Afghanistan. Ptolemy took Egypt and the important dyeing industries. Seleucus created a new capital city, Antioch, which he founded in 300 BC on the banks of the Orontes River, where it flows from Syria into Turkey. This was to become one of the most important cities of its time in the east, rivaling even Alexandria.

He founded another city, on the Tigris not far from the modern city of Baghdad, and named it after himself, Seleucia. Antioch communicated with the Mediterranean and was linked - by the roads built by Darius - with the cities of Anatolia and Mesopotamia; Seleucia, in today's Iraq, lay close to the headwaters of the Arabian Gulf and on the caravan route to Palmyra. The two cities were thus ideally located across a number of intersecting trade routes. The old Medean capital of Ecbatana lay on the route that ultimately led to China, although at this date there is as yet no evidence of organized commercial exchange.

The stage, however, was set, and information about China - garbled, shrouded in legend - began to percolate into the Greek-speaking cities of the Seleucids. At the same time, Greek artisans, painters and musicians who had flocked to the frontier cities founded by Alexander in Persia and today's Afghanistan - each a classic Greek city, complete with baths, temples and public meeting places - began to spread their influence into Central Asia by means of trade and travel along the Silk Roads.

This report reached the ears of the Han emperor Wu as a result of a mission he sent westward in 138 BC in order to form an alliance with a nomadic group that the Chinese histories call the Yue-zhi. His goal was to oppose a huge tribal confederation formed by the Xiong-nu, who may have been the people we know as Huns, and who were threatening China's borders. The mission was led by Zhang Qien, who followed the ancient route to Kashgar, where he was unfortunately captured and held prisoner by the Xiong-nu. Eventually he succeeded in escaping and making his way back to China, bringing valuable reports of affairs in Central Asia, and most interestingly, of Bactria, where he had actually been.

By this time, Bactria and Sogdiana were no longer part of the Seleucid Empire, the eastern portions of which had fragmented into independent satrapies or been conquered by the Parthians, another nomad people of uncertain origins. But Bactria - today's Balkh, in northern Afghanistan - preserved its character as a Greek city. Zhang Qien was surprised to see Chinese products - bamboo and cloth - there, and asked where they had been obtained. He was told that they had been bought in India.

Bactria was joined to India by a 4,200-kilometer (2,600-mile) road that passed across the Hindu Kush, through the Khyber Pass and drove diagonally across the subcontinent to the Bay of Bengal, following the course of the Ganges. It was built by Chandragupta, founder of the Maurya dynasty, who met and befriended Alexander in 325 BC, and who, two years later, drove the Greeks out of India. He ruled northern India from his capital of Pataliputra - on the site of modern Patna - where he maintained friendly intercourse with the Greeks of Bactria and beyond, despite the defeat he inflicted on Seleucus in 305 BC.

A Greek ambassador named Megasthenes spent a number of years at Chandragupta's capital and, in about 302 BC, wrote a long and fascinating description of it, which contains the earliest certain reference to trade with China. He says that in the bazaars of Pataliputra goods from Mesopotamia, the Greek cities of Asia Minor, and China were available; he specifically mentions silks, embroideries and brocades, all of Chinese origin, as well as medicinal plants, ivory, gold, jewels, and rugs - these last probably from western Asia and Mesopotamia.

The Chinese trade goods seen by Megasthenes in Pataliputra may well have reached India overland from China; if so, this is evidence that the Silk Roads were operating even before the Qin and Han Dynasties.

It is certain, however, that Indian trade goods, art objects and ideas were passing north along Chandragupta's road to Taxila, across the Hindu Kush to Bactria, and then spreading through Central Asia, reaching China along the Steppe Route and the Imperial Highway.

Zhang Qien's visit to Bactria was much later - some 47 years after the fall of the Mauryan Empire, which came to an end in 185 BC. But the bamboo and cloth he saw were not the only Chinese products to reach Bactria. The Bactrian kings, struck beautiful cupro-nickel coins, the earliest of which were minted in 170 BC - long before Zhang Qien's visit. In view of the high melting point of nickel, which was beyond the reach of the technology of the time, the metal of which these coins are made must be a natural alloy. Since this particular alloy only occurs in the Chinese province of Yunnan, there must have been trade in ore or metal between Bactria and China.

Yet nowhere is such trade mentioned. Other archeological discoveries in the Bactrian area also show how little we actually know of the trans-Asian trade of the second century BC. Coins - probably passed from hand to hand by tribesmen - have been found near Lake Balkash, in the Kazak Soviet Socialist Republic, which were minted near the Bosporus in the fourth century BC; a charming glass vase made in Alexandria in the second century BC has been found on the banks of the Yellow River, in the heartland of China. A gold cup with a richly embossed floral design, made somewhere in the Hellenistic world, has been found in Siberia. All of these finds are probably a result of "relay trade" - or perhaps of booty taken by nomad bands - but they still show how far goods could travel from their points of origin.

Zhang Qien finally returned to Xian after an absence of 13 years, the original 100 members of his mission reduced to two. He brought news of many lands and peoples unheard of in China - Ferghana, Parthia, Bactria, Babylonia, Syria and India. The impact on the Chinese was comparable to the impact on the Greeks of the conquests of Alexander: New worlds - and new markets -were opened, and China's isolation ended.

Many Chinese embassies were dispatched to Central Asia in order to procure the fabled horses of Kokand, a city on the Jaxartes River in the region of Ferghana - horses which Zhang Qien had failed to bring back to his emperor.

Because the Chinese had finally crushed the Xiong-nu in 121 BC and settled garrisons in the Gansu Corridor, where the Imperial Highway passes beyond the protection of the Great Wall, these embassies were able to travel unharmed across the Tarim Basin. And when the people of Kokand repeatedly refused to part with their fine breeding stock, the Emperor Wu launched a 60,000-man army against the city, capturing it in 102 BC after a bitter siege. At a single stroke, China gained dominion over the entire Tarim Basin, the vital key to the Silk Roads.

Four years earlier, the Chinese had sent an embassy to the Parthian ruler Mithridates II, who had come to the throne in 124 BC and established Parthian rule throughout Persia and Mesopotamia. The Chinese embassy had been joyfully received in the Parthian capital of Hecatompylos - "City of a Thousand Gates" - where they were particularly intrigued by the Syrian jugglers and acrobats they saw. The Parthians in turn sent their ambassador to Xian, and the diplomatic relations thus established between China and the Parthians of the Iranian plateau were to endure hundreds of years. The two nations - and their successors - controlled the vital and most dangerous stretches of the Silk Roads, and - as long as such intermediaries as the Sogdians co-operated - the precious silks of China and their superb steel weapons could be exchanged for the furs, gold, jade, horses and carpets coveted by the Chinese.

The alliance did not last long - but long enough for the Byzantines to perfect their own silk-making techniques, and to transform cities like Damascus, Beirut, Aleppo, Tyre and Sidon into famous centers of silk production. They were to remain so after the coming of Islam, and to become the cities from which medieval Europe obtained its luxury fabrics.

The ancient Indo-European trading and agricultural peoples of Central Asia were now almost all subject to Turkish-speaking masters. They - and the Chinese - were fortunate that these Turks were not united, for it was their disunity that allowed Chinese power to penetrate so far into Central Asia.

Li Shi-min's troops moved along the Silk Roads, and between 630 and 640, with much bloodshed, made themselves masters of the towns of Kucha, Khotan, Kashgar, Yarkand and Turpan:Their control of the Tarim Basin was complete. Their conquest took place at a time when the Sassanian Dynasty of Persia was particularly weak, still reeling from the blows the Byzantines had dealt it shortly before. The lack of a powerful state south of the Oxus helped make the Chinese incursions into Central Asia possible and contributed to the speed with which the Turkish khans submitted.

At the same time, China was expanding to the east, into Korea and Southeast Asia, and was also pursuing aggressive policies to the north. A measure of the success of this expansion was the adoption in Korea, Annam and Japan of the Chinese script. For the first time in her long history, China was opening up the world around her.

The primary motive of China's expansion, however, was military: As always, she was trying to protect her frontiers from barbarian incursions. The problem had become particularly pressing with the movement southward of huge numbers of Turko-Mongol nomadic pastoralists. Each wave of migration set off another, and the ripples that had reached western Europe under Attila and his hordes, little more than a century before, were but a small reflection of the human tidal wave that threatened to engulf China.

It is a great irony of history, however, that the real threat to China's control of Central Asia should come from a land and a people of which it is unlikely Li Shi-min had ever heard.

In 632, the year Chinese troops took Kashgar and the last Sassanian shah, Yazdagird, ascended the throne of Persia, the Prophet Muhammad died in Medina, an oasis city in western Arabia. He was the messenger through whom a new religion was revealed. Islam took firm hold on the Arabian Peninsula during his lifetime, and within a few years of his death would establish itself throughout the Middle East. Medina was an important stage on the ancient Incense Road to South Arabia, and Muhammad himself had earlier engaged in the caravan trade with Syria - even dealing, according to some accounts, in silks from Manbij. He had undoubtedly heard of China, although as yet China knew nothing of him.

The speed and success of the Muslim conquests are well known; in the years immediately following the death of Muhammad, Egypt, Syria, Mesopotamia, most of Asia Minor and Persia had been conquered. In 651 the Sassanian Yazdagird was killed in Marv -that huge oasis on the Golden Road, some 230 kilometers (140 miles) southwest of the Oxus, which was to play such an important role in early Islamic history. The Sassanian Dynasty was at an end, although Yazdagird's son Peroz, with Chinese help, made a heroic attempt to regain his ancestral lands. The long-standing friendship between Persia and China, begun perhaps as far back as the time of Alexander, is symbolized by the fact that Peroz died in exile in the Chinese capital of Xian.

Despite the rapidity of the Arab expansion, and the fact that the conquest of Persia meant that Afghanistan and even part of what is now Pakistan were in Arab hands, it was some time before their attention turned to Central Asia, the territory across the Oxus which the Arabs called "What Lies Beyond the River."

There were the famous cities of Bukhara and Samarkand, still strongholds of the Sogdians, as they had been since at least the time of Alexander, who married a Sogdian princess in Samarkand. To the northwest was Khwarizm, where the Oxus flows into the Aral Sea; to the northeast, beyond the Jaxartes - the Shash to the Arabs, the Syr Darya to the Turks - were Ferghana and Tashkent. All these ancient cities of the Golden Road were under the control or influence of the Sogdians, who in turn had come to an uneasy alliance with the Turks.

Using Marv as a base, the famous Arab general Qutaiba ibn Muslim crossed the Oxus in 711 and took Bukhara. Samarkand, still a center of the Buddhist faith, fell the following year. Qutaiba immediately pushed on to the Jaxartes, which he crossed, and took Ferghana - which was still exporting horses to China, at the staggering price of 40 bales of silk a head.

In 713, Qutaiba sacked Kashgar - the first Chinese city attacked by the Muslims. The Chinese emperor Xuan-zong requested Qutaiba to send a delegation to Xian, 3,200 kilometers (2,000 miles) from Kashgar, to explain Arab aims arfid perhaps to hear Chinese exhortations not to disrupt the trade routes to the West. This delegation is mentioned in both Arab and Chinese annals, and was the beginning of a long series of embassies between Muslim rulers and the Chinese court.

In 751, at one of the great turning points of Islamic history, just as the Muslim Umayyad Dynasty of Syria was being replaced by the Abbasids of Iraq, the Chinese made a last attempt to assert their control over Central Asia. They sent an army commanded by a Korean general into Ferghana, home of the splendid horses so loved by the Emperor Wu. The Muslim army inflicted a crushing defeat on the Chinese at Talas - capturing Chinese paper-makers and silkweavers in the process - and the Chinese withdrew behind the Great Wall, never to attempt Central Asia again.

In 763 Baghdad was founded on the banks of the Tigris as the new Abbasid capital. A circular city with four gates, it was intended to express by its physical form the unity of the new faith. From then until the fall of the Tang Dynasty in 907, Baghdad and Xian were in close communication. A southern arm of the Silk Roads entered the circular "City of Peace" through the Khorasan Gate; far to the east, the network reached the square city of Xian, its streets a grid laid out according to cosmological principles. Both cities were filled with men of every faith, language and nationality.

Unlike the Romans, and the Greeks before them, the Arabs communicated directly with China, both by land and by sea - showing a marked preference for the latter. Even the Romans had had to buy silk at marked-up Parthian prices, but the Arabs, whose empire stretched from the borders of China to Spain, were their own middlemen. They were also silk producers themselves, greatly extending the Syrian silk industry begun under Justinian; by the ninth century they rivalled China in their production.

The Tang Dynasty's love of foreign luxuries eventually ruined them in much the same way that Rome had been debilitated by the drain on its economy caused by the earlier silk trade. But the dynasty survived until 907, and its intellectual achievements and art have remained a byword till the present day.

By the 10th century Buddhism, Manicheism and Zoroastrianism had virtually ceased to exist in Central Asia. The majority language had become Turkish, the majority faith Islam. Central Asia had fully entered the cultural orbit of the Middle East, and was no longer as open as it had once been to Chinese and Indian influences. Samarkand and Bukhara became rich and grew into large metropolises.

The murder of 450 Muslim merchants at a place called Otrar in the year 1218 changed the face of Central Asia, and indeed, of the world, for it triggered the most devastating invasion of steppe nomads in history. Among the merchants was an envoy of Genghis Khan, leader of the Mongol hordes. He punished this interference with free trade on the steppes by unleashing 200,000 men, first against Otrar, then against Samarkand. Soon all of Central Asia and Persia had felt the wrath of the Mongols: More than five million people were killed in these two areas alone. The cities of Bukhara, Samarkand, Tashkent, Balkh and Marv were sacked with terrible loss of life.

Genghis Khan's sons conquered China and devastated Iraq. They destroyed Baghdad in 1258, murdering the last Abbasid caliph, and one of them, Kubilai, founded the Mongol Yuan Dynasty in China in 1260.

Oddly, one of the results of the Mongol conquest was closer links between East and West. The Mongols ruled from the Mediterranean to the Pacific, and controlled the Steppe Route to Europe through Russia. For the first time, envoys from Europe as well as merchants were able to travel safely under Mongol protection from Europe to China. Marco Polo is the most famous of the many Europeans who made their way east during the so-called "Mongol peace," which lasted more than a century, and it was at this time that Europe and China first came into direct contact.

It may seem strange that European powers such as the Venetians, the French under Louis IX, and even the Pope should attempt to make contact with the dread Mongols - the self-styled "scourges of God."

But in the Mediterranean basin, this was the time of the Crusades. The small Christian principalities on the Syrian and Palestinian coast were greatly threatened by the Seljuq Turks, who had taken the initiative in the Muslim reconquest of Crusader territories. The Christians thought that by allying themselves with the Mongols they could together put an end to Muslim power in the Levant and Asia Minor.

Indeed, the Venetians had already taken advantage of the Mongol occupation of the northern steppes to set up trading colonies on the shores of the Black Sea, and Venetian intelligence agents had already made contact with the Mongol court in Karakoram.

Genghis Khan was determined that his empire should not prove as ephemeral as some that had preceded it. Before his death in 1227, he began setting up an efficient civil service and a network of post roads with relay stations and - perhaps most important of all - settling the question of succession. That was the rock upon which so many previous dynasties had come to grief, barely outliving their founders. It is interesting that Genghis Khan, who was almost certainly illiterate, hired Chinese advisers - experienced civil servants - to establish and administer his state.

Genghis Khan's sons and grandsons continued his policies in a remarkable example of family solidarity. In 1260 Kubilai, grandson of Genghis, was elected Great Khan of the Mongols and it was to his court that the Polos of Venice made their way.

They had been preceded by a few years by a papal emissary named John of Plano Carpini, who in 1246 made his way to the encampment of one of Ghenghis Khan's grandsons, Kuyuk, with a message from the Pope urging him to be baptized and rally to the Christian cause. Since Kuyuk was a thorough pagan, this message fell on deaf ears, and John of Plano Carpini returned to Europe with a sobering account of Mongol realities. The Vatican Library still retains letters from the Mongol khans in response to these rather naive embassies; they are beautifully written and quite insulting.

John was followed by another Franciscan emissary, named William of Rubruck, whose account of his trip to the court of Great Khan Mongke in 1255 is one of the most informative and lively accounts of Mongol society ever written. But manuscripts of the Itinerarium were not widely circulated in the Middle Ages - only five are at present known - and his account, intelligent and observant as it is, would have sunk into oblivion had Roger Bacon not made an abstract of it in his Opus Maius.

The opposite is true of Marco Polo's famous account of his trip to Khanbalik - today's Beijing - a few years later. Il Milione, as it came to be known, was copied and recopied, and when printing was invented went through numerous editions. It has remained one of the most popular books of travel ever written.

The Polos were a family of Venetian merchants who established themselves first in Constantinople, then in the Venetian trading posts of the Black Sea. Before Marco Polo's birth, his father, Nicolo, and his elder brother Mafeo visited Bukhara, where by great good luck they met Mongol officials who invited them to visit Kubilai Khan. They were apparently the first Europeans Kubilai had ever encountered, and he charged them to deliver a message to the Pope, asking him to send a delegation of Christians to take part in a public debate between various faiths. Unlikely as it may sound, this was a favorite pastime of the Mongol court.

The Polos finally made their way back to Venice after an absence of more than 15 years. Nicolo discovered that his wife had borne him a son shortly after his departure from Venice so many years before; this was Marco, who later accompanied his father and his uncle on their return trip to the Mongol court, begun in 1271.

The Polos sailed to Acre, crossed Syria and Iraq - where they saw the effects of the Mongol sack of Baghdad - and made their way across Central Asia to Balkh. They crossed the Pamir Mountains, passed through Kashgar and Khotan and, after crossing the terrible desert of Lop, reached Dunhuang and the Gansu Corridor. Eventually they made their way to Khanbalik and met Kubilai, apparently entering his service. They stayed in China for some 17 years.

Marco Polo's account of China is the first description of that country in a European language, and the Polos appear to be the first Europeans ever to travel the whole length of the Silk Roads. It was not until the Jesuit missions of the 17th century that more scientific accounts of the country began to appear.

When Marco Polo finally returned to Venice and talked of his travels, he was not believed; he - and his account of China, dictated to a cellmate while in prison years later - were dubbed Il Milione, "The Million Lies." It was not until the careful researches of Sir Henry Yule at the end of the 19th century that it was shown how accurate his descriptions of China were.

The last empire of the steppes was the one founded by Tamerlane, who claimed descent from Genghis Khan. At the head of a vast horde of Turks and Mongols, he took Balkh in the year 1370; within 30 years, he had made himself master of Central Asia, India, Persia and the Middle East. His descendants, the Moghul kings of India, ruled until the 19th century.

The century after Tamerlane's death saw the emergence of powerful centralized states in the Middle East - the Ottoman Turks, political heirs of the Seljuqs, in the west and the Safavid Dynasty in Persia. Central Asia gradually declined in importance, much of it becoming grazing land for Uzbek tribesmen filtering south. The Uzbeks occasionally formed states, but Muslim Central Asia - now beginning to be known as Turkestan, the land of the Turks -never recovered its economic importance.

The Portuguese discovery, in the late 15th century, of the sea route around the Cape of Good Hope to India very quickly led to direct sea trade between Europe and the Far East. Central Asia was no longer the crossroads of the world, and the nomads of the northern steppes, though superb horsemen and warriors as always, were no match for the Ottoman and Safavid armies equipped with the latest firearms. The nomads turned their attention to the vast lands of Russia, and the Middle East and China no longer trembled to their hoof-beats. Samarkand, Bukhara, Ferghana and Tashkent, the once-great cities of the Golden Road, preserved only the romance of their names and the vague memory that once, long ago, they had somehow been important.