Shannan is a prefecture level city under the jurisdiction of the Xizang Autonomous Region. It is located between 90 ° 14 ′ -94 ° 22 ′ E and 27 ° 08 ′ -29 ° 47 ′ N. It is located in the south of Gangdise Mountain to Nyainqen Tanggula Mountain, in the middle and lower reaches of the Yarlung Zangbo River, in the north of Xizang's capital Lhasa, in the west of Shigatse, in the east of Nyingchi, in the south of India and Bhutan. Shannan has a boundary line of more than 600 kilometers long, which is a very important strategic location. With an average altitude of 3700 meters, it is called "the valley of southern Tibet", and is the southwest border of China.