The McMahon Line region. The line was the focus of a brief war in 1962, when Indian and Chinese forces struggled to control a disputed area (shown in red), much of which is a high altitude wasteland. The
Line of Actual Control (LAC) in the eastern sector of the border is broadly the
McMahon Line agreed between
British India and
Tibet in 1914. Even though China regards the line as "illegal", on the grounds that Tibet was not an independent power, it agrees to abide by it as an LAC. However, the line has never been demarcated on the ground and the inadequate surveying of 1914 leaves several areas uncertain, open to dispute between the two sides. China also has an underlying claim to the entire state of
Arunachal Pradesh, which it calls "South Tibet", and the claim is especially strong for the
Tawang district, which was the birthplace of the
6th Dalai Lama of Tibet. The Tawang area was indeed under some form of
suzerainty of Tibet at that time, but it was relinquished by Tibet in signing the agreement for the McMahon Line.
Yangtse plateau and environs near the
Chumi Gyatse Falls: marked by the US
Office of the Geographer in 2012 (in blue) vs
OpenStreetMap in 2022 (in dark green). The difference between them is believed to be the alteration made by India in 1986. Yangtse, the region which was the site of the clash, is essentially a
plateau that adjoins the LAC. It is part of a larger area called
Mago-Chuna in the mountainous and thickly forested part of the Tawang district. Yangtse is bordered to the north by an LAC that is a continuous ridgeline of high mountain peaks that range in elevation from to over . The ridgeline, with its crest reaching an elevation of over , roughly runs in a southwest–northeast direction to the
Tulung La mountain pass, and affords observation over much of the surrounding area, including the roads leading to the all-important
Sela pass, which provides India's gateway to the Tawang region. The Chumi Gyatse Falls, at about from the LAC, form the most prominent landmark in Yangtse, and mark the juncture between the two prominent ridgelines of the area; namely, the Bum La ridgeline to its southwest, and the
Tulung La ridgeline to its northeast. The McMahon line in this area was thus altered. The control of the Tulung La ridgeline accrues an advantage of military
high ground to the Indian troops in Yangtse. Indians maintain a network of layered defences in the region, with a small detachment of forward troops maintaining a chain of six forward defensive
outposts on the ridgeline. Although lightly held, these serve to establish the extent of its frontier with China. Complementing the outposts is an Indian forward base of about battalion strength, emplaced about south of the ridge. India also maintains a more significant military presence in valleys adjoining the Yangtse plateau, with precarious steep dirt tracks providing the only access to the higher ground. In contrast, the Chinese hold positions at lower elevations on the plateau, which places its troops at a tactical disadvantage. However, qualitative improvements to military and transport infrastructure on the Chinese side of the border accruing from its investments has greatly enhanced its capacity to mobilize troops. == Background and significance ==