Southern Central Region of China, is largely an agricultural area but is home to considerable industry as well. This area is generally poorer than the coastal provinces on the east and southern coasts and is the main source of migrant laborers for those provinces. The regions of Sichuan and Chongqing are classified and referred to as West China on the mainland because of its location at the extremity of China proper even though they geographically lie in central China. West Sichuan, with its historic links to Tibet lies at edge of the region, and is also the gateway to the frontier/minority regions of Tibet (TAR) and Xinjiang. Chongqing is historically and culturally part of Sichuan, but is now administratively a separate municipality and a mega-city in its own right.