Ngari Prefecture or Ali Prefecture is a prefecture of China's Tibet Autonomous Region covering Western Tibet, whose traditional name is Ngari Khorsum. Its administrative centre and largest settlement is the town of Shiquanhe. It is one of the least densely populated areas in the world, with 0.3 people per kilometer.

Shiquanhe, known in Tibetan as Sênggêkanbab or Sênggêzangbo, is the main town and administrative seat of Ngari Prefecture, Tibet Autonomous Region, China. Shiquanhe is located on the bank of Sênggê Zangbo, the source stream of the Indus River, close to its confluence with the Gartang River.