If Chinese economic growth and technological achievements significantly shaped the Eurasian world of the third-wave era, that pattern of interaction was surely not a one-way street, for China too was changed by its engagement with a wider world. During this period, for example, China had learned about the cultivation and processing of both cotton and sugar from India. From Vietnam, around 1000, China gained access to the new, fast-ripening, and drought-resistant strains of rice that made a highly productive rice-based agriculture possible in the drier and more rugged regions of southern China. This marked a major turning point in Chinese history as the frontier region south of the Yangzi River grew rapidly in population, overtaking the traditional centers of Chinese civilization in the north. In the process, the many non-Chinese peoples of the area were painfully overwhelmed by Chinese military forces and by the migration of at least a million Han Chinese farmers by 1400. Some of them were attracted by new economic opportunities, while others were forcibly relocated by the Chinese state, intent on thoroughly integrating the south into Chinese civilization.

Technologically as well, China’s extraordinary burst of creativity owed something to the stimulus of cross-cultural contact. Awareness of Persian windmills, for example, spurred the development of a distinct but related device in China. Printing arose from China’s growing involvement with the world of Buddhism, which put a spiritual premium on the reproduction of the Buddha’s image and of short religious texts that were carried as charms. It was in Buddhist monasteries during the Tang dynasty that the long-established practice of printing with seals was elaborated by Chinese monks into woodblock printing. The first printed book, in 868 C.E., was a famous Buddhist text, the Diamond Sutra.

A further transforming impact of China’s involvement with a wider world derived from its growing participation in Indian Ocean trade. By the Tang dynasty, thousands of ships annually visited the ports of southern China, and settled communities of foreign merchants—Arabs, Persians, Indians, Southeast Asians—turned some of these cities into cosmopolitan centers. Buddhist temples, Muslim mosques and cemeteries, and Hindu phallic sculptures graced the skyline of Quanzhou, a coastal city in southern China. Occasionally the tensions of cultural diversity erupted in violence, such as the massacre of tens of thousands of foreigners in Canton during the 870s when Chinese rebel forces sacked the city. Indian Ocean commerce also contributed much to the transformation of southern China from a subsistence economy to one more heavily based on producing for export. In the process, merchants achieved a degree of social acceptance not known before, including their frequent appointment to high-ranking bureaucratic positions. Finally, much-beloved stories of the monkey god, widely popular even in contemporary China, derived from Indian sources transmitted by Indian Ocean commerce.