The Kunlun Mountains (simplified Chinese: 昆仑山; traditional Chinese: 崑崙山; pinyin: Kūnlún Shān, pronounced [kʰu̯ə́nlu̯ə̌n ʂán]; Uyghur: كۇئېنلۇن تاغ تىزمىسى / قۇرۇم تاغ تىزمىسى ), pronounced [хөндлөн уул] / (Khundlun meaning horizontal in Mongolian) constitute one of the longest mountain chains in Asia, extending for more than 3,000 kilometres (1,900 mi). In the broadest sense, the chain forms the northern edge of the Tibetan Plateau south of the Tarim Basin.

The exact definition of Kunlun Mountains varies over time. Older sources used Kunlun to mean the mountain belt that runs across the center of China, that is, Altyn Tagh along with the Qilian and Qin Mountains. Recent sources have the Kunlun range forming most of the south side of the Tarim Basin and then continuing east, south of the Altyn Tagh. Sima Qian (Records of the Grand Historian, scroll 123) says that Emperor Wu of Han sent men to find the source of the Yellow River and gave the name Kunlun to the mountains at its source. The name seems to have originated as a semi-mythical location in the classical Chinese text Classic of Mountains and Seas.