Tianwendian
Tianwendian is the Chinese name for the northern Aksai Chin region near the Karakoram Pass, which is referred to as Depsang Plains in India. A border outpost established in the area in the 1980s is currently the main reference point for Tianwendian. Lying in the Chip Chap River valley close to China's Line of Actual Control with India, it serves as the military headquarters for the Tianwendian region.
Name
Tianwendian means "astronomical point" in Chinese. The first two characters "tiānwén" is the Chinese word for "astronomy." The name is said to have been used to describe a military defence area in northern Aksai Chin in the run-up to the 1962 Sino-Indian War. The region was also referred to as the "sky defence area". The name is an obvious allusion to the high elevation of the area, reported as 6200 metres above sea level.The region extends till the next defence area to the south, viz., Heweitan.
The Depsang Bulge area has been referred to as the "South Tianwendian Valley",
its river Burtsa Nala as "Tiannan",
and its mountain pass to the Jeong Nala valley as the "Tianhexi Pass"—the "western pass between Tian and He". In this respect, Tianwendian is the Chinese equivalent of India's "Depsang Plains".
In the 1980s, a specific outpost named Tianwendian was established close to China's Line of Actual Control with India's Daulat Beg Oldi sector. Now it is more common to use the name to refer to the outpost than the defence area.
Military outpost
China originally established a military outpost in 1959 at Point 5243, which is at an elevation of 5243 meters above sea level.It was composed of a border company.
In the run up to the 1962 war, China called the entire area Tianwendian Defence Area and used the Point 5243 post as its headquarters.
The newer Tianwendian post was established after the 1962 war. China said it was an astronomical observatory. A few years later India realised that it was an not an observatory but a military post. Over the years, China has continued to expand the post.
Around the time of the 2013 Daulat Beg Oldi incident, PLA constructed a radar station, an 11 m radome at an elevation of 5530m, at this outpost.