During the Song Dynasty, Nagqu was called one of the Four Northern Tribes (). In 1269, the Mongolian soldiers began to garrison in the northern Tibet, and later the "39 Tribes of Hor" (, ) formed Mongolian forces in northern Tibet. In 1731, the Qing Government placed the territory of 39 Tribes under the direct jurisdiction of the Amban. In 1751, Kanxiang Dzong () in Nagqu was formed to the direct rule of the Kashag Government, and part of the area was under the jurisdiction of Panchen. Around the Xinhai Revolution, the government of the Kashag Government relegated the region of 39 Tribes to its rule and forcibly took over the Panchen Lama. In 1916, the "Hor Director" () was established. In 1942, the prefecture of Changchub Chikyab (, ) was formed. In 1951, the seat of Changchub Chikyab Prefecture was Nagqu (Heihe) Town, the prefecture administered the pasture land to the northern Lhasa and 6 dzongs in Heihe area, the Conference Hall of Panchen Chamber () administered Damusajia Dzong (). The prefecture of Changchub Chikyab had jurisdiction over 14 dzongs in 1954. The Preparatory Committee of Tibet Autonomous Region set up Chikyab Office () in Nagqu in October 1956, The prefecture of Changchub Chikyab was renamed to Heihe in 1959, the prefecture of Heihe was renamed to Nagqu in January 1960, its seat was Heihe County (modern Seni District). The former Nagqu Prefecture was approved for prefecture-level city status on October 2, 2017, by the State Council, and it was officially established on May 7, 2018. Geography and climate Nagqu is located in the northeast of Tibet. Nagqu Town is by the China National Highway 109 northeast of Lhasa. Nagqu is bordered by Bayingolin and Hotan Prefectures of Xinjiang to the north, Haixi, Yushu Prefectures of Qinghai and Chamdo to the east, Nyingchi, Lhasa and Shigatse to the south, and Ngari Prefecture to the west. It covers an area of .) It lies on the southern slope of Tanggula Mountains, on the north side of Nyenchen Tanglha Mountains, and on the eastern end of the Changtang Plateau. The average altitude is more than above sea level. Principal towns in the region include Nagqu Town, Amdo, Nyainrong and Xainza. Nagqu is extremely rich in water resources, with a total surface water resources of about 54 billion cubic meters, groundwater resources of about 25.1 billion cubic meters and a further 8.8