The Depsang Bulge or Burtsa Bulge
is a 900-square-kilometre area
of mountain terrain in the disputed Aksai Chin region, which was conceded to India by China in 1960, but has remained under Chinese occupation since the 1962 Sino-Indian War. The area is immediately to the south of the Depsang Plains and encloses the basin of the Burtsa Nala (or Tiannan River, ), a stream originating in the Aksai Chin region and flowing west to merge with the Depsang Nala near the village of Burtsa in Ladakh, eventually draining into the Shyok River. The area is perceived to be of strategic importance to both the countries, sandwiched by strategic roads linking border outposts. Since 2013, China has made attempts to push the Line of Actual Control further west into Indian territory, threatening India's strategic road.
Geography
The Depsang Bulge is immediately to the south of the Depsang Plains. The "bulge", in theoretical Indian territory (had China's 1960 claim line been implemented), encloses the basin of the Burtsa Nala ("Tiannan River" to the Chinese), one of five rivers that drain into the Shyok River after rising in Aksai Chin. Near the campsite of Burtsa, a halting place on the traditional caravan route, the Depsang Nala flowing from the north joins the Burtsa Nala. The combined river flows west to join the Murgo Nala near Murgo and eventually drains into the Shyok River. All the streams bring snow-melt water, reaching the highest volume in the afternoons, and diminishing to practically nothing at other times.
The Depsang Bulge contains the basin of the upper course of the Burtsa Nala, to the east of Burtsa and the traditional travel route. Based on various Indian news reports, it would appear that the Depsang Bulge area is over 19 km long east to west and about 5 km wide, giving an area of roughly 900 km2. Burtsa is at an elevation of 4800 metres, the source of Burtsa Nala at 5300 metres, and the surrounding hills rise up to 5500–5600 metres. Just beyond the hills to the south is another nala called the Jeong Nala ("Jiwan Nala" to the Indian military, "Nacho Chu" or "Nao Chu" on older maps), which does not have a "bulge" (Map 2).
Numerous tributary streams from the surrounding hills drain into the Burtsa Nala within the Depsang Bulge. Of particular note are two streams, both joining the main nala near a location called "Y-junction". The northern stream, Raki Nala, flows down from the Depsang Plains and hence, connects the Depsang Bulge to the Depsang Plains. The southern stream connects it to the Jeong Nala valley. Indian troops have traditionally used these two valleys to patrol the periphery of the Depsang Bulge.
Chinese claim lines
The so-called 1956 claim line of China is part of the "Big map of the People's Republic of China", published in 1956. It has special significance in that Chinese premier Zhou En-lai certified it to the Indian premier Jawaharlal Nehru, in a December 1959 letter, as showing the correct boundary of China. The Chinese boundary in this map ran east of all but one of the rivers that drain into the Shyok River. (Map 2, green line)
In June 1960, when the Chinese delegates met the Indian delegates for border discussions, they revealed a new expanded boundary, which has come to be called "the 1960 claim line". This line dissected all the rivers that drained into Shyok, except for the Burtsa Nala. (Map 2, brown line) Why the Burtsa Nala should have been singled out for this special treatment has not been explained. But the resulting "bulge" in the Indian territory around the Burtsa Nala has been dubbed the Depsang Bulge in popular parlance.
1962 war
Prior to the 1962 war, the Indian Army had established half a dozen posts on the hills to the north of the Depsang Bulge. These were mostly of platoon to section strength, manned by Jammu and Kashmir Militia (Ladakh Scouts). The Chinese PLA launched its attack on 20 October 1962, with overwhelming strength, a superiority of 10 to 1 in numbers, and eliminated most of them. The remaining posts were recalled to Burtsa and other rear locations. The Chinese forces advanced to their 1960 claim line in most locations.
However, at Depsang Bulge, the Chinese troops advanced further than the 1960 claim line, "straightening out the bulge". (Map 2, orange line, and Map 3, yellow line) Thus, a third line emerged, from the ceasefire line of 1962. More detailed maps of the ceasefire line show a smaller bulge in Indian territory at the mouth of the valley. The US Office of the Geographer's "Large-Scale International Boundaries" (LSIB) dataset shows this boundary (red line in Map 4).