Kelsu lake in the Tien Shan Mountains

Tian Shan (China: 天山, pinyin: Tian Shan, literally "celestial mountains" Mongol: Тэнгэр уул, Tenger Uul; Uighur: تەڭرى تاغ July: Tengri Tagh), also spelled Tien Shan, is a major mountain system located in Central Asia. The highest peak in the Tian Shan is Victoria Peak (Jengish Chokusu), 7439 meters (24,406 feet).

The Chinese name Tian Shan can be derived from the name Qilian Xiongnu (祁连), which was seen by Yuezhi Shiji as the homeland, and is said to refer to the Tian Shan, rather than the range of 1500 km (930 mi) to the east now known by that name. The proximity Tannu-Ola Mountains (Tuvan: Таңды-Уула Tangdy-Uula) has the same name ("Heaven / Heavenly Mountain" or "god / spirit mountain").