Persian Empire
Deep Dive 11 min read

The Silk Road and the Persian Empire

Sima Qian, writing in the late first century BCE, tells us that the Parthian kings controlled the trade in Chinese silk, and that the Parthian Empire was one of the four great powers of the day, along with Han China, the Indian kingdoms, and Rome. He is doing two things at once: giving us the earliest sustained description of the overland trade between China and the Mediterranean, and giving us the earliest record of a Parthian strategy to keep that trade in their own hands. From the moment the Han emperor Wu sent the envoy Zhang Qian westward in 138 BCE — and Zhang Qian returned with the first real account of the Parthian and Bactrian kingdoms — until the Mongol conquests of the thirteenth century, when the new Mongol world order briefly opened the routes to direct east-west traffic, the Persian empires stood astride the Silk Road and derived a substantial part of their wealth from the transit trade between East and West.

The English literature begins with Peter Frankopan’s The Silk Roads: A New History of the World (2015), Valerie Hansen’s The Silk Road: A New History (2012), Warwick Ball’s The Eurasian Exchange (2016), and D. T. Potts’s The Arabian Gulf in Antiquity (1990) and his chapter on the Gulf in the Oxford Handbook of Ancient Iran (2013). Richard Frye’s The Golden Age of Persia (1975) and The Heritage of Central Asia (1996) are still useful. For the Sasanian period, Geo Widengren’s “The Status of the Jews in the Sasanian Empire” in the Cambridge History of Iran and the more recent work of M. J. G. Kestemont, Peter Huyse, and G. Gnoli give the institutional context. Étienne de la Vaissière’s Sogdian Traders (2002, English 2005) is the standard on the Sogdian commercial network, and Susan Whitfield’s Life Along the Silk Road (2015) is the best introduction to the personal-history approach. The UNESCO Silk Roads Programme, launched in 1994 and revived in 2013, has been the principal international coordinating body.

The opening of the Silk Road

The Silk Road was effectively opened in the second century BCE by the Chinese Han dynasty. The Han emperor Wu, in 138 BCE, sent the envoy Zhang Qian westward to seek an alliance with the Yuezhi peoples against the Xiongnu, the dominant nomadic power of the eastern steppe. Zhang Qian’s mission was a failure in its immediate political aim, but it opened China’s eyes to the markets of Central Asia and the wealth of the Parthian and Roman worlds. Within a few decades, Chinese silk, lacquer, iron, and other manufactured goods were travelling west in substantial quantities, in exchange for horses, jade, glass, and gold.

The opening of the Silk Road had a transformative effect on the Iranian world. The Parthian Empire, which ruled Iran and Mesopotamia in the early centuries of the Silk Road, was ideally placed to profit from the new trade. The Parthian kings imposed customs duties on the caravans, protected the merchants, and used the wealth to finance a great expansion of cities, palaces, and coinage. Sima Qian records that the Parthian state was one of the great powers of the day, that its kings ruled from a splendid capital, and that the merchants of the empire controlled the trade in silk and other eastern luxuries.

The Parthian middleman

The Parthians were not passive middlemen. They actively shaped the Silk Road traffic to their advantage, refusing to allow direct contact between the Roman and Chinese empires and keeping the prices of eastern goods high in the Mediterranean. The famous story of Gan Ying, the Chinese envoy sent to seek an alliance with Rome in 97 CE, illustrates the point. Gan Ying reached the Parthian court and was there dissuaded from continuing westward; he returned to China convinced that the Parthian Ocean (the Mediterranean) was unnavigable and that direct contact with Rome was impossible. The Parthian motivation, as Chinese historians later realised, was commercial: they did not wish to share the profits of the silk trade with the Chinese.

The Parthian silk trade, like the coinage and the silver plate, was a major element of the empire’s economic power. Parthian silks, woven in the workshops of Mesopotamia, the Iranian plateau, and the Central Asian provinces, were exported across the Roman world; the Roman Senate repeatedly tried to restrict the consumption of silk, in part because of the drain on the imperial treasury. The Parthian control of the Silk Road also had a major cultural effect: Buddhist, Manichaean, and Christian ideas travelled along the trade routes, and the early centuries of the Common Era saw a substantial exchange of religious and philosophical traditions between East and West. The Sogdian merchants of Central Asia, who became the principal commercial agents of the early Islamic Silk Road, were the heirs of the Parthian-era commercial network.

The Sasanian control of the Silk Road

The Sasanian Empire, which succeeded the Parthians in 224 CE, inherited and intensified the Parthian control of the Silk Road. Under rulers such as Shapur I and Khosrow I Anushirvan, the Sasanian state developed a sophisticated system of tariffs, caravanserais, and diplomatic treaties designed to maximise the imperial share of the trade. The Sasanian kings negotiated treaties with the Sogdian, Bactrian, and Tokharian principalities of Central Asia, with the Indian powers of the subcontinent, and with the Byzantine Empire — the principal peace treaty is the so-called Eternal Peace of 532 CE and the subsequent peace of 562 CE between Khosrow I and Justin II, not Justinian I (who died in 565; the 562 treaty was the result of negotiations that had been ongoing under Justinian I, but the final agreement was signed by his successor Justin II). The treaties typically included provisions for the protection of merchants, the regulation of tariffs, and the exchange of diplomatic gifts.

The silk monopoly of Khosrow I

The most famous act of Sasanian control of the silk trade was the imperial silk monopoly established by Khosrow I in the sixth century. According to the Greek historian Procopius (Wars 8.17.1–8), the Sasanian king had previously bought silk from the Chinese and sold it to the Byzantines at a substantial markup. The Byzantines, aggrieved by the price, attempted to break the monopoly; the most famous such attempt was the smuggling of silkworm eggs from Central Asia to Byzantium, traditionally attributed to two monks acting on the orders of Justinian I, probably in the 550s CE. The story is probably apocryphal, but it captures the reality: the silk trade was a major source of geopolitical tension.

The Sasanian state derived substantial revenue from the Silk Road transit trade. The Persian Gulf ports of Siraf and Hormuz, the Mesopotamian cities of Ctesiphon, Baghdad (after its foundation in 762), and Tikrit, and the Iranian cities of Rayy, Isfahan, and Merv were all major nodes of the overland and maritime trade. The great Sasanian city of Ctesiphon, on the Tigris, was the commercial capital of the late antique east, and its population, perhaps half a million people in the sixth century, was sustained in large part by the trade of the Silk Road.

Cities of the Persian Silk Road

The great cities of the Persian Silk Road were the principal nodes of the transit trade. Each was a major commercial centre, with its own specialised products, its own merchant communities, and its own role in the wider network.

Merv, in modern Turkmenistan, was the eastern gateway of the Persian-controlled Silk Road. The city, founded in the Achaemenid period as a provincial capital, was the principal city of the Khorasan region and a major stop on the overland routes from China to the Mediterranean. Merv was conquered by Alexander the Great, by the Parthians, and by the Sasanians, and under the Sasanians it became the capital of the eastern provinces. The city was famous for its textiles, in particular its woollen and silk fabrics, and as a centre of learning and religion. Merv was the home of the great mathematician al-Khwarizmi (780–850 CE) and a major centre of Islamic learning in the early caliphal period. Merv was destroyed by the Mongols in 1221 CE.

Nishapur, in the Khorasan region of northeastern Iran, was the second great city of the eastern Persian world. The city was founded by the Sasanians as a new capital for the Khorasan region and became, under the early caliphs, one of the great centres of the Islamic world. Nishapur was famous for its pottery, its textiles, and its turquoise mines. The city was a major node of the Silk Road trade, and its merchants, the nisapuri, were known across the medieval world.

Bukhara, in modern Uzbekistan, was the third great city of the Persian-controlled Silk Road. The city was the capital of the Samanid dynasty in the ninth and tenth centuries and a major centre of Persianate culture, learning, and trade. The Samanids, who ruled from Bukhara, were great patrons of Persian poetry, and the city was the home of the great poet Rudaki, often called the father of Persian poetry. Bukhara was a major stop on the overland routes from China to the Mediterranean, and it was a centre of the slave trade, in particular the Samanid traffic in Turkish slaves who would rise to positions of great power in the Islamic world.

Rayy, near modern Tehran, was the principal city of the central Iranian plateau. The city was founded in the Achaemenid period and was a major centre of the Persian art and architecture tradition; the Sialk ziggurat near Kashan and the Sasanian palace of Firuzabad are both products of the central Iranian tradition. Rayy was a major stop on the routes from Mesopotamia to the east, and its merchants, brokers, and bankers were active across the medieval world. The city was destroyed by the Mongols in 1220 CE, but its memory lived on in the work of the great Persian poets.

Goods of the Silk Road

The Silk Road carried a vast range of goods between East and West. Silk was the most famous, but the trade included many other products. From China, the caravans brought silk, of course, but also paper, porcelain, jade, and rhubarb. Tea and gunpowder, the two commodities that one sometimes sees listed, are anachronistic for the Persian-controlled Silk Road: gunpowder was a Tang invention of the ninth century, used militarily rather than as a trade good, and tea did not become a major trade item until the Mongol period and later. From India, the routes carried cotton textiles, spices (pepper, cinnamon, cardamom), gems (diamonds, rubies, sapphires), pearls, ivory, and indigo. From Central Asia, the routes brought horses, carpets, lapis lazuli, and precious stones. From Iran and Mesopotamia, the trade included Persian carpets, silver plate, glass, dates, and the products of the great Iranian textile and metalwork industries. From the Roman and Byzantine world, the Silk Road carried gold, silver, glass, wine, olive oil, and various manufactured goods. The slave trade was a substantial component of Silk Road traffic, with Turkish, Slavic, and African slaves travelling in both directions.

Sasanian diplomacy and the Peace of 562

The Sasanian state was a major diplomatic player on the Silk Road. The so-called “Peace of 561” between the Sasanian king Khosrow I and the Byzantine emperor Justin II — the treaty was signed in 562, with negotiations that had been ongoing under Justinian I — included detailed provisions for the regulation of the silk trade, with Sasanian silk to be sold to Byzantium at fixed prices and the proceeds to be divided between the two empires. The treaty also included provisions for the extradition of political refugees, the regulation of border trade, and the conduct of diplomacy. The Peace of 562 is one of the earliest surviving international trade agreements and a vivid illustration of the importance of the Silk Road to the Sasanian and Byzantine economies.

The Sogdian merchants

The Sogdians, an Iranian people of Central Asia whose homeland lay in the Zeravshan valley of modern Uzbekistan, were the principal commercial agents of the Sasanian and early Islamic Silk Road. The Sogdian merchants, who spoke a Middle Iranian language and used a Sogdian script derived from the Aramaic alphabet, established communities at every major node of the trade, from Samarkand and Bukhara in the east to Chang’an in China and to the bazaars of Baghdad and Damascus in the west. The Sogdian language and script became the lingua franca of the Silk Road in the early medieval period, and the Sogdian merchants carried not only goods but also religions, particularly Manichaeism, Zoroastrianism, and Buddhism, between the major civilisations of Eurasia. Frantz Grenet’s work on the Sogdian merchants (in La Sogdiane et ses voisins, 2011, and elsewhere) and de la Vaissière’s Sogdian Traders (2002) for the Iranian side, the working references. The recently published Sogdian merchant letters from the early fourth century, the so-called “Ancient Letters” from a watchtower near Dunhuang, give us the closest thing we have to the voices of Silk Road merchants in their own words.

The decline of the Persian Silk Road

The Sasanian control of the Silk Road was broken by the Arab conquest of the seventh century. The Arab caliphs, who ruled from Damascus and later Baghdad, redirected the trade through their own territories and undermined the Iranian commercial position. The Mongol conquests of the thirteenth century, which destroyed many of the major cities of the Iranian world — Baghdad in 1258, Merv in 1221, Nishapur in 1221 — further weakened the Persian role in the Silk Road, although the Pax Mongolica briefly restored a cosmopolitan trade. The rise of maritime trade in the Indian Ocean, the European voyages of discovery in the fifteenth and sixteenth centuries, and the Ottoman control of the eastern Mediterranean all combined, in the early modern period, to shift the centre of the trade away from Iran.

The legacy of the Silk Road in the Persian-speaking world

The legacy of the Silk Road is still visible in the modern Persian-speaking world. The cities of the Iranian plateau, in particular Isfahan, Shiraz, Tabriz, and Mashhad, retain the architectural and commercial heritage of their Silk Road past, and the great bazaars of these cities are still major centres of the regional trade. The Persian carpet industry, which has its roots in the Silk Road period, continues to be a major element of the Iranian economy. The Persian language, written in a modified Arabic script, became one of the great literary languages of the Islamic world, and Persianate culture, centred on the cities of Iran and Central Asia, has had a profound influence on the wider world.

For further reading

  • Frankopan, Peter. The Silk Roads: A New History of the World (2015).
  • Hansen, Valerie. The Silk Road: A New History (2012).
  • Ball, Warwick. The Eurasian Exchange (2016).
  • Potts, D. T. The Arabian Gulf in Antiquity (1990) and his chapter in the Oxford Handbook of Ancient Iran (2013).
  • Frye, Richard N. The Golden Age of Persia (1975) and The Heritage of Central Asia (1996).
  • de la Vaissière, Étienne. Sogdian Traders: A History (2002, English translation 2005).
  • Whitfield, Susan. Life Along the Silk Road (2015).
  • Widengren, Geo. “Iran, the Hebrew Bible, and the Sasanian Empire” in Peoples, Old and New, in Mesopotamia (1984).
  • Kestemont, M. J. G. “Iran and the Sasanians” in The Cambridge History of Iran III.2.
  • Grenet, Frantz. La Sogdiane et ses voisins (2011) and his articles on the Sogdian merchants.