The Silk Road, a term that first appeared at the end of the nineteenth century, refers to that network of caravan tracks traversing Central and West Asia, used to carry trade goods between the East and West from approximately the second century B.C. to the fifteenth century A.D. These tracks were neither a single road nor was silk the only commodity that was carried across them. The termini of the “Road” were said to be Rome in the West and Chang’ an in the East.

The economic importance of silk for Rome, where it often amounted to as much as 90 percent of their imports from the East, is no doubt responsible for its prominent association by Western scholars with these caravan routes. The technology of silk production had existed in China from as early as 1500 B.C. Silk became one of China’s most lucrative exports from at least the second century on, leading the state to institute laws making the technology of silk production a strictly guarded secret. Persons caught attempting to carry out of China this secret or the material for its cultivation (caterpillar eggs of the silk moth, genus Bombyx, or mulberry leaves) were subject to execution. This policy was an apparent success, since the Romans were kept unaware even of its material source. Ptolomy wrote that it was made from the hairs on certain tree leaves. Even the Sasanian Persians, who were the primary middlemen in the silk trade for hundreds of years, were unable to produce their own silk until the sixth century A.D. It was then, according to traditional accounts, that a Nestorian Christian monk managed to smuggle caterpillar eggs out of China hidden in his staff, one of the earliest, perhaps legendary, accounts of industrial espionage.

As important as silk was to both Rome and China, it was by no means the only commodity of value passing over the Silk Road. Precious gems and metals, such as jade and gold, were also basic commodities. In addition, horses from Ferghana, foodstuffs and cultigens—such as apricots, melons, and raisins—and manufactured goods such as lacquer from China were in great demand at various points along the Road. Moreover, it is a matter of dispute whether silk was even the most significant or important item of all that changed hands and cultures along the Road, since along with silk and the other commodities, flowed peoples, technologies, and religions. Most significant of the latter were Indian medical technologies, as well as the religions of Buddhism and Islam. Amidst the culturally diverse Buddhist communities across Central Asia, Greek, Indian, and Chinese artistic techniques and sensibilities blended, producing a rich and varied iconography that has come to be associated not just with Central Asia but with China, Korea and Japan as well.

The Routes
Setting out west from Chang’an, Silk Road caravans crossed the Yellow River at Lanzhou, and then passed up the Gansu Corridor to Jiayu Guan Pass, where the Road departed China proper. Due west lay 1,200 miles (1,931 km) of trackless desert, the Gobi and the Takalamakan, bounded much of the way on the north and the south by two parallel mountain ranges, the Tian Shan and the Kun Lun. The width of the desert between these mountain ranges averages 250 miles (402 km). With an average annual rainfall of less than an inch, traversing this barren waste would have been all but impossible except for the existence of a chain of oasis communities, some constituting autonomous states, ringing the deserts on both sides. These oases obtained their water from melting Ice Age glaciers in the surrounding mountain ranges.

At Jiayu Guan the Silk Road split into northern and southern routes, moving between oases. The southern route passed first through Dunhuang, the site of the Maogao Buddhist cave complex, and thence, through Miran, Khotan, and Yarkand before rejoining the northern route in Kashgar at the western edge of the Tarim Basin. The northern route passed through Hami, Turfan, and Kuqa, rejoining the southern route in Kashgar some 1,200 miles (1,931 km) later. From Turfan on the northern route, caravans had the further option of turning northwest and proceeding up through Urumqi, and into the steppe region of Kazakstan, and thence east toward Samarkand. From Yarkand on the southern route or from Kashgar, a primary caravan route turned south across the Karakhoram into the Upper Indus region and on into the Gangetic plain of India.

Caravans continuing west from Kashgar again had the option of taking a northerly or southerly course across the Pamirs, “the Roof of the World.” The southern route passed through the Wakan Corridor to Balkh in modern Afghanistan and on to Merv at the eastern edge of the old Persian Empire. The northern route crossed the Pamirs near the Ferghana Valley, and from there continued through Samarkand to Merv. In Persia the Silk Road joined other well-established trade routes, most passing through Ctesiphon (later Baghdad) in the Tigris-Euphrates valley. From there cargoes and travelers continued either to one of several seaports on the eastern Mediterranean, and then by ship to Rome, or overland through modern Turkey to Constantinople and across eastern Europe.

Because of the extreme dryness throughout most of Central Asia, many fabrics, dyes, woods, texts, and even human bodies underwent little deterioration. Consequently, the sites listed above generally all have been extremely rich in artifacts and architectural remains of ancient and medieval Central Asian cultures. Worthy of note are the city remains of Kuqa and Khotan, and those surrounding Turfan: Jiaohe and Gaochang. At the beginning of the twentieth century these sites all yielded rich troves of artifacts to the numerous European and Japanese expeditions that competed with each other in the race to lay claim to the Central Asian heritage. The great preponderance of artifacts were Buddhist paintings, scriptures, and sculpture uncovered in sand-buried caves and ruined monasteries. Also found, though in lesser quantity, were religious artifacts produced for Nestorian Christian, Manichaean, and Zoroastrian communities along the routes.

History
It has traditionally been assumed that trade began in the second century B.C., as the result of a daring journey by a Chinese military commander, Zhang Qien, who was commissioned by the Han Emperor, Wudi, to explore the possibility of an alliance with the Persian Empire against their common nomadic enemy, the Xiongnu. Though captured several times, Zhang was able in each case to escape, eventually establishing contact with the Persians before returning to China. He had traveled over 3,000 miles (4,800 km), and in addition to negotiating a trade agreement with the Persians, he arranged for the import of a powerful new breed of war horse from Ferghana, contributing greatly to China’s military strength. He also brought back reports of a country he rendered in Chinese as Li-jian, assumed by most scholars to be Rome. Silk trade was officially sanctioned in the second century B.C. by Wudi, and continued with only minor interruptions until the breakup of the Mongol Empire and the collapse of the Mongol Yuan dynasty in the fifteenth century. Trade was conducted in numerous stages, few if any traders traveling the entire route. The Mongol Empire had extended almost the entire length of the Silk Road, and under its protection, from the thirteenth to the fifteenth centuries, travelers and goods moved across the length of Asia in relative security. It was during this period that Marco Polo traveled the entire route from Italy to Khanbalik (modern Beijing). Also in the thirteenth century Rabban Sauma, a Chinese Nestorian Christian, made the same journey in the opposite direction, from Khanbalik to Rome, and then on into western Europe. The journey accounts of these two figures are rich in data on medieval Asia. With the collapse of the Mongol Empire and the opening of the East-West sea routes, which afforded merchants greater control and far less risk, the Silk Road was almost totally abandoned, and faded almost completely from European consciousness.

Archaeological Discoveries
Whereas this history has generally been borne out by texts and archaeological discoveries, recent findings have greatly extended the time frame during which the Silk Road functioned as a conduit of major importance between East and West. Analysis of strands of silk found in the hair of an Egyptian mummy dating from about 1000 B.C. reveal technologies of weaving and production almost certainly specific to China. This predates earlier assumptions on the beginning of silk trade by at least eight hundred years. Such silk would almost certainly have come by the land route across Central Asia. Similar samples of Chinese silk found in seventh-century B.C. German graves and fifth-century B.C. Greek tombs have provided additional evidence for an earlier commencement of the silk trade than previously assumed. If these current studies are borne out, then all that can be said of the second-century B.C. date is that it marks the beginning of trade officially sanctioned by the Chinese Emperor.

This discovery of silk outside of the immediate Roman world of antiquity extends not only the time frame, it extends the length of the Silk Route, as well. In some respects Nara, Japan, might be regarded as an Eastern terminus. In the twelve-hundred-year-old Shosoin located in Nara there exists a large imperial collection of eastern European, Persian, and Central Asian goods. Unique examples of glass, both silk and non-silk textiles, Buddhist images, and musical instruments are to be found in the collection. These goods, which all arrived in Japan before 752 when they were gathered in the Shosoin, could have come only by the Silk Route. Due to the highly sophisticated preservation technology incorporated in the structure built to house them, they in many cases constitute the sole remaining examples of such goods, and have been the basis for many modern identifications of lost technologies.

Extending the frame even further are contemporary speculations on migrations from Africa into Central Asia and China one million years ago via the routes followed later by the silk trade. Eighty-thousand-year-old artifacts have recently been found in the Pamirs, and others, 20,000 years old, have been found in the deserts of Central Asia. Recent discoveries of twelve-thousand-year-old Caucasian mummies at “Red Hill” near Urumchi on the northern Silk Route suggest a greater ethnic diversity in Central Asian communities than previously suspected.