The Subei Mongol Autonomous County is an autonomous county within the prefecture-level city of Jiuquan in the northwest of Gansu Province, China, bordering Xinjiang to the west, Qinghai Province to the southeast and Mongolia's Govi-Altai Province to the north. Containing the northernmost point in Gansu, Subei is split into two non-contiguous sections and has an area of 66,748 km2 (25,772 sq mi) and had approximately 13,046 inhabitants in 2000. To the east it shares a border with Ejin Banner, Alxa League, Inner Mongolia.

Jiuquan, formerly known as Suzhou, is a prefecture-level city in the northwesternmost part of Gansu Province in the People's Republic of China. It is more than 600 km (370 mi) wide from east to west, occupying 191,342 km2 (73,878 sq mi), although its built-up area is mostly located in its Suzhou District.