At least 20 Indian soldiers were beaten to death on Monday in a clash with Chinese border forces in the Galwan Valley of the Ladakh region. In May, near Lake Pangong Tso, melees broke out several times and Indian soldiers were badly injured. Similar stories of military clashes between India and China over their 3,500-kilometer frontier have been repeated for the last six decades.

Sixty years ago, there was no such thing as a border conflict between India and China, because Tibet was a buffer zone between the two giant Asian countries. The first-ever Indo-China war, over a border conflict, occurred in 1962, three years after China completely occupied Tibet in 1959. Chinese troops advanced against unprepared Indian forces in two Himalayan border posts, killed more than 1,000 Indian soldiers and imprisoned more than 3,000.

In 1967, the second Indo-China war over the Nathu La and Cho La border regions took the lives of another 88 Indian soldiers. Then two bloodless yet extremely intense skirmishes took place, one over the Sumdorong Valley in Arunachal Pradesh in 1987 and the other at Daulat Beg Oldi in the Ladakh region in 2013.

In 2017, an Indo-China brawl over the Doklam border broke out, with troops on both sides suffering injuries.

Besides these major confrontations, countless smaller skirmishes between the two countries’ border patrols have occurred, almost on a weekly basis, according to the Indian Defence Review.

The decades of diplomacy and negotiations between the world’s two most populous countries over their Himalayan border contentions never made any progress, and both sides are always highly skeptical of each other’s willingness to make any adjustments. This is because both countries are held back by the historical complexities related to Tibet’s political status.

In 1684, the Treaty of Tingmosgang (གཏིང་མོ་སྒང་ཆིངས་ཡིག) was signed between Tibet and the Ladakh kingdom to settle their borderline, which was continuously regarded even after Maharaja Gulab Singh Jamwal invaded and annexed Ladakh to Jammu under the suzerainty of the Sikh Empire in 1834.

Between 1913 and 1914, the representatives of British India, Tibet and China gathered in Shimla to settle the political status of Tibet and Tibet’s relations with China. As a part of the Shimla Convention, British India and Tibet signed an Indo-Tibet border treaty establishing the McMahon Line, which mainly defined the eastern Himalayan international borderline.

However, the Shimla Convention failed to find a feasible mutual ground, and thus China finally refused to sign the treaty. In 1949, the Chinese Communists successfully defeated the Kuomintang and founded the People’s Republic of China. Chairman Mao Zedong immediately declared a “liberation plan” for Tibet and began to claim that Tibet was always a part of China.

Subsequently, under the principle of peaceful co-existence, Indian prime minister Jawaharlal Nehru signed the Panchsheel Treaty in 1954 and India became the first country in the world to recognize China’s sovereignty over Tibet.