Bayingolin Mongol Autonomous Prefecture, often abbreviated to Bayingol (literally "rich river"), is an autonomous prefecture of the People's Republic of China, bordering Gansu to the east, Qinghai to the southeast, and the Tibet Autonomous Region to the south. It is the largest prefecture-level division nationally, with an area of 462,700 km² (178,600 sq mi), larger than even neighbouring Gansu.