The Silk Road

The first is imperial, and it treats the whole thing as foreign policy.

Zhang Qian's intelligence failure got a military answer. Between one hundred and twenty one and one hundred and nineteen, Han armies drove the Xiongnu out of the Hexi corridor, the strip of usable ground between the Tibetan plateau and the Gobi, and garrison towns went in behind them. Those four towns were the gateway for the next fifteen hundred years.

The frame the court used was the tribute system. Foreign rulers sent embassies with gifts and received Chinese goods and Chinese titles in return.

Which means that in the Chinese record there is no trade. There is the natural movement of goods toward the centre of civilisation, and merchants who are tolerated, occasionally celebrated, and never equals.

The Protectorate of the Western Regions, set up in sixty before the common era, administered the oasis states of the Tarim basin as dependencies. Not partners. Dependencies.

The second account belongs to the people who actually ran it, and almost nobody has heard of them.

The Sogdians came from the Zerafshan valley, from Samarkand and Bukhara and Panjakent. They spoke an eastern Iranian language, wrote in a script out of Aramaic, and did business in at least seven languages. Their inscriptions turn up from Mongolia to the Black Sea.

In the Tang capital they controlled the wine trade and the horse trade and much of the banking. They ran the postal relay stations. Their caravanserais stood in every oasis from Turpan to Merv.

And Sogdiana was never an empire. It was a set of city states, each run by its own merchant families.

That is the whole reason you have not heard of them. Empires write histories. City states write contracts.

In nineteen oh seven an archaeologist pulled a bundle of letters out of a ruined Chinese watchtower. They are Sogdian, they date to about three hundred and thirteen, and they describe the collapse of a Chinese dynasty, the sack of a capital and the famine after it, from ground level, in commercial correspondence. Exchange rates. Prices. Debts. And a woman named Miwnay, stranded, writing to a husband who has not sent for her.

The third account follows the texts.

In six twenty nine a monk called Xuanzang left the Tang capital illegally. Travel beyond the frontier was forbidden. He crossed the Gobi alone and nearly died of thirst. A Buddhist king in Turpan held him for a month, wanting him as a court monk. He went over the Tian Shan in summer, when the passes were barely open.

He spent sixteen years in India, most of them at Nalanda, a monastic university in Bihar holding ten thousand monks.

He came home in six forty five with six hundred and fifty seven Buddhist texts, a hundred and fifty relics and seven statues, and the emperor who had forbidden the journey received him as a hero.

Then the part nobody plans. Xuanzang wrote up a hundred and thirty eight kingdoms in detail. Twelve hundred years later, when the British began the Archaeological Survey of India, they used that seventh century Chinese travel diary to find the Buddhist sites India had forgotten, including Nalanda itself.

The fourth account turns on a battle that almost nobody counts as important.

In seven fifty one an Abbasid army and a Tang army met at the Talas river, in what is now Kyrgyzstan. The Arabs won. Neither side followed it up. As battles go it decided nothing.

Among the Chinese prisoners were papermakers.

Within a few decades there were paper mills in Samarkand. Baghdad had one by seven ninety three. By nine hundred, paper had replaced papyrus and parchment across the Islamic world. By eleven hundred it was in Spain. By fourteen fifty Gutenberg was printing on it.

And the Abbasid capital sat at the western hub of the whole network. The House of Wisdom, founded around eight thirty, translated Greek, Persian, Indian and Chinese works into Arabic. Euclid, Ptolemy, Aristotle, Galen and the Indian mathematician Aryabhata all passed through Baghdad on their way to medieval Europe.

The fifth account says the network's most consequential export was not a technology.

The caravanserais that sheltered merchants sheltered rats. The ships that carried pepper carried fleas.

Genomic work on plague strains, published in the last decade, puts the origin of the Black Death in Central Asia, near the Tian Shan. At a cemetery by lake Issyk-Kul there is a spike of burials in thirteen thirty eight and thirteen thirty nine, and some of the tombstones name the cause. Pestilence.

From there it travelled the trade network west. In thirteen forty six a Mongol army besieging a Genoese post in Crimea is reported to have thrown plague dead over the walls. Genoese ships left for Constantinople, then Messina, then everywhere.

In seven years it killed somewhere between seventy five and two hundred million people. A third to a half of Europe, and comparable shares of the Middle East and Central Asia.

The road that carried paper carried that.