The Tian Shan ("celestial mountains"), also commonly spelled Tien Shan, and known as Tangri Tagh ("celestial mountains" or "mountains of the spirits") in the Uyghur language, is a mountain range located in Central Asia.
The now widely-used name Tian Shan is a Chinese translation of the Uyghur name, which may in turn go back to a Xiongnu name, qilian reported by the Shiji as the homeland of the Yuezhi, which has been argued to refer to the Tian Shan rather than to the range 1,500 km further the east now known by this name. Another mountain range located in the general vicinity, the Tannu-Ola Mountains , also bears a synonymous name ("heaven/celestial mountains" or "god/spirit mountains").
The range lies to the north and west of the Taklamakan Desert in the border region of Kazakhstan, Kyrgyzstan and the Xinjiang Uyghur Autonomous Region of western China. In the south it links up with the Pamir. It also extends into the Chinese province of Xinjiang and into the northern areas of Pakistan and some parts of Jammu and Kashmir where it meets with Hindu Kush.
In western cartography the eastern end of the Tian Shan is usually understood to be just west of Ürümqi, while the range to the east of that city is known as the Bogda Shan. However, in Chinese cartography, from the Han Dynasty to the present, the Tian Shan is also considered to include the Bogda Shan and Barkol ranges.
The Tian Shan are a part of the Himalayan orogenic belt which was formed by the collision of the Indian and Eurasian plates in the Cenozoic era. They are one of the longest mountain ranges in Central Asia, stretching some 2,800 km eastward from Tashkent in Uzbekistan.
The highest peak in the Tian Shan is Jengish Chokusu which, at 7,439 m or 24,406 ft, is also the highest point in Kyrgyzstan and is on the border with China. The Tian Shan's second highest peak, Khan Tengri (Lord of the Spirits), at 7,010 m, straddles the Kazakhstan-Kyrgyzstan border. Mountaineers class these as the two most northerly peaks over 7,000 m in the world.
The Torugart Pass, 3,752 m or 12,310 ft high, is located at the border between Kyrgyzstan and China's Xinjiang province. The forested Alatau ranges, which are at a lower altitude in the northern part of the Tian Shan, are inhabited by pastoral tribes speaking Turkic languages. The major rivers rising in the Tian Shan are the Syr Darya, the Ili river and the Tarim River. The Aksu Canyon is a notable feature in the northwestern Tian Shan.
One of the first Europeans to visit and the first to describe the Tian Shan in detail was the Russian explorer Peter Semenov in the 1850s.