In prehistoric times the region was apparently divided into the eastern Ba and western Shu kingdoms , which may have amalgamated during the Shang era (1600-1100 BC). Sites at Sanxingdui , near Chengdu, suggest the Ba-Shu was a slave society with highly developed metalworking skills and bizarre aesthetics. Agricultural innovations at the end of the third century BC opened up eastern Sichuan to intensive farming, and when the Qin armies stormed through, they found an economic base which financed their unification of China in 221 BC - as did Genghis Khan's forces almost 1500 years later. In between, the area became the Three Kingdoms' state of Shu - a name by which Sichuan is still sometimes known - and later twice provided refuge for deposed emperors.

Otherwise too distant to play a central role in China's history, the region leapt to prominence in 1911, when government interference in local rail industries sparked the nationwide rebellions that toppled the Qing empire. The next four decades saw rival warlords fighting for control, and, though some stability came when the Nationalist government made Chongqing their capital after the Japanese invaded China in 1937, nominally independent states persisted within the former Sichuan's borders as late as 1955: "When the rest of the country is at peace, Sichuan is the last to be brought to heel", went the saying. The province suffered badly during the Cultural Revolution - Jung Chang 's autobiography, Wild Swans, gives a first-hand account of the vicious arbitrariness of the times in Sichuan - and was left, by the early 1970s, poor and agriculturally devastated. Typically, it was the first province to reject Maoist ideals, when party leader Zhao Ziyang allowed farmers to sell produce on the free market, spearheading the reforms of fellow native Sichuanese, Deng Xiaoping . So effective were these reforms, that by the 1990s Sichuan was competing vigorously with the east coast economy; a situation for which Chongqing - the already heavily industrialized gateway river port between Sichuan and eastern China - claimed a large part of the credit, and its economic weight finally secured the city and its surrounds separate provincial status. Meanwhile, development continues across the region, bringing all the problems of runaway growth: appalling industrial pollution, ecological devastation, and an unbelievable scale of urban reconstruction.