Qilian Mountain, also known as Nan Shan (literally "Southern Mountains", as it is to the south of Hexi Corridor), is a northern outlier of the Kunlun Mountains. It lies between Qinghai and the Gansu provinces in northwest China. The average elevation of Qilian Mountain is between 4,000 and 6,000 meters. The altitude at 4,000 meters is called the "snow line".