The Sichuan Basin , or Szechwan Basin, is a lowland region in southwestern China. It comprises the central and eastern portions of Sichuan province, and the neighboring Chongqing Municipality (which itself was part of Sichuan until 1997). Due to its relative flatness and fertile grounds, it is heavily populated with a population of more than 100 million. In addition to being a dominant geographical feature of the region, the Sichuan basin also constitutes a cultural sphere that is distinguished by its own unique customs, cuisine, and dialects. It is also called the "Red Basin." It is famous for rice cultivation. It is also the principal gas-producing region of China.