Dependent on Indian relics and teachings, Chinese clergy faced a "borderland" complex, but China developed as a Buddhist centre in its own right by the 8th century. Some key developments included relic worship at the Famen monastery and its role in Tang dynastic politics, Mount Wutai as the abode of the bodhisattva Manjusri, and, drawing on ideas of Buddhist decline in India and regeneration in China, the cult of Maitreya. The latter culminated in Wu Zetian's adoption of the title; her reign was "arguably the most vibrant era in the history of Sino-Indian interactions, and ... perhaps marked the highest point in Indic influences on Chinese society".
Buddhist links between India and China persisted after the 9th century: monks and relics moved in both directions and during the Song dynasty there was an official translation project, though it was plagued by a shortage of translators and reused older work. But,
"by the end of the tenth century, Buddhism in India and China had taken two very different paths. While Indian Buddhism developed its own philosophical and ritualistic (esoteric) traditions, the Chinese clergy formulated and propagated their own indigenous teachings. This divergence ... ended the millennium-long epoch of a vigorous Sino-Indian intercourse stimulated by the transmission of Buddhist doctrines and pilgrimage activity."
This was one factor in the reconfiguration of Sino-Indian trade. Others were a possible decline in urbanism in North India, the movement of sugar-making technology to China, the spread of Islam, and the more mercantile outlook of late Tang and Song China and of South Indian kingdoms such as the Cholas.
"Prior to the tenth century, Sino-India trade was founded on and supported by the network of mercantile groups that either adhered or were sympathetic to the Buddhist teachings. ...
By the mid-eleventh century, traders from Muslim diasporas dominated almost every circuit of Indian Ocean commerce from the Chinese coast to India and beyond."
In a wider context, long-term changes in Sino-Indian trade can be connected to the global networks studied by world systems theorists, the stability of Central Asia, Chola raids on Southeast Asia, Chinese foreign policy under the Ming, and the spread of trading diasporas in both directions.
This summary does little justice to the wealth of detail Tansen Sen provides in Buddhism, Diplomacy, and Trade. It is not a narrow monograph, however: the more technical material is left to eighty pages of endnotes and the approach is broad. This is a work which will make details of Buddhist doctrine interesting to economic historians and trade links interesting to students of religion.