Chang'an

Xuanzang left Chang'an in 629 against an imperial ban on travel, crossed the deserts and the mountains, studied for years at Nalanda in India, and came back in 645 with hundreds of manuscripts, images and relics. The emperor who had forbidden the journey received him publicly, and the Great Wild Goose Pagoda was raised in the city to store what he had brought.

What followed was industrial. Buddhist translation in China was a collective operation with defined roles: a master who construed the Sanskrit, assistants who checked the sense against other recensions, scribes, and stylists who made the Chinese readable, all working under state support. Xuanzang's team produced an enormous body of text in twenty years and established a Chinese version of the Yogacara school on the strength of it. His own account of the journey, written for the throne, described the kingdoms and monasteries he had passed through in such detail that nineteenth century archaeologists used it to locate Indian Buddhist sites that Indian tradition had forgotten.

He was not the first. Kumarajiva had been brought to Chang'an as a captive at the start of the fifth century and translated there under the same kind of patronage, and it is his versions of the Lotus and Diamond sutras, not the more literal later ones, that East Asian Buddhists have chanted ever since. A city that could feed and house such teams, and a state willing to pay for them, is why so much Indian Buddhist literature survives in Chinese when the Sanskrit is lost.

A stone slab set up in 781 and rediscovered in the seventeenth century records, in Chinese with Syriac names down the side, that a missionary named Alopen reached Chang'an in 635, that his scriptures were translated and examined at imperial order, and that a decree permitted the teaching to be practised. The Church of the East called itself the luminous religion in Chinese, and the stele is the single most important document of Christianity's first arrival in China, describing doctrine in vocabulary borrowed from Buddhism and Taoism because no other vocabulary existed.

It was not alone. Manichaeans obtained official recognition in the Tang capital, largely through the Uighur allies who had adopted the religion; Zoroastrian fire temples served the Sogdian merchant communities; and Muslim traders were present from early in the dynasty, with the Great Mosque of the city traditionally dated to this period. Chang'an at its height was probably the most religiously mixed city on earth.

That ended abruptly. In 845 the emperor Wuzong, a Taoist by conviction and a treasury by necessity, ordered the suppression of Buddhism: thousands of monasteries were closed, hundreds of thousands of monks and nuns returned to lay life, bronze images were melted for coin, and monastic land was confiscated. The foreign religions were swept up in the same edicts. Chinese Buddhism recovered, though the scholastic schools never regained their position. The Church of the East, Manichaeism and Zoroastrianism in China effectively did not.