Sichuan Basin
During the period of the Three Kingdoms, the Sichuan Basin was at the centre of another independent Shu State, until it was reunified with China in the 3rd century CE by the Jin dynasty. Around this time the basin's population is estimated to have been 1 million, with Chengdu the leading city. After the collapse of the Tang Dynasty in 907, the Sichuan Basin became home to a third Shu state, this time lasting only two decades. During successive Chinese dynasties, the Sichuan Basin was firmly integrated with Greater China. Mass migration occurred during the Ming Dynasty as the basin became one of the primary rice-producing regions of China. The basin's population fell sharply in the 17th century due to devastation caused by famine, war, and possible genocide. After this time, the basin was repopulated with emigrants from China, further assimilating the unique cultures and peoples inhabiting the basin. During the Second Sino-Japanese War when much of Eastern China was occupied by Japanese forces, Chongqing in the Sichuan Basin served as the Republic of China's capital.