China–India border

A border in three pieces

The border is usually described in three sectors. The western sector is Aksai Chin, next to India's Ladakh. The middle sector runs along the Indian states of Himachal Pradesh and Uttarakhand. The eastern sector follows the McMahon Line beside Arunachal Pradesh and Sikkim. On the Chinese side it runs mostly along the Tibet Autonomous Region.^[5] Aksai Chin itself lies largely in Xinjiang.^[2]

Nepal and Bhutan sit between the sectors, which is why the map shows three separate stretches. The shortest is Sikkim's, where the Dongkya Range forms the border with Tibet.^[6] An 1890 agreement defined the Sikkim–Tibet border when Sikkim was a kingdom under British paramountcy. Sikkim became an Indian protectorate in 1950 and an Indian state on 16 May 1975.^[6]

The two countries have never agreed where the whole line runs. Their 1993 agreement calls it the “line of actual control” and says both sides will “jointly check and determine” the segments where their views differ.^[1] In Aksai Chin, Chatham House describes that line as “not so much a line but a buffer zone”, with each side reading the claim lines differently.^[5]

The McMahon Line

In October 1913, representatives of the British Empire, China and Tibet met at Shimla, a hill station in the Himalayan foothills, to negotiate boundaries.^[3] One result was a line between Tibet and British India, named after the chief British negotiator, Sir Henry McMahon. It runs about 890 km from the eastern border of Bhutan along the crest of the Himalayas to the northwestern tip of Myanmar.^[3]

Britain and Tibet accepted the terms. China refused to sign the main agreement, because it held that Tibet was part of China and had no power to make treaties.^[3] In 1959 the Chinese premier Zhou Enlai wrote to India's prime minister Jawaharlal Nehru that the line had “never been recognised by any Chinese Central Government”.^[3]

India upholds the McMahon Line as its boundary with China. China claims Arunachal Pradesh as part of southern Tibet, calls it Zangnan, and shows it as Chinese on official maps.^[3] Chatham House points out that China accepted the same line as its border with Myanmar.^[5]

“The so-called McMahon Line was a product of the British policy of aggression against the Tibet Region of China and has never been recognised by any Chinese Central Government and is therefore decidedly illegal.”^[3]

Aksai Chin and the 1962 war

Aksai Chin is a high, cold, almost uninhabited plateau, a southwestern extension of the Plateau of Tibet. The Karakoram Range bounds it to the west and the Kunlun Mountains to the north.^[2] For a long time it was an ignored corner of the subcontinent. That changed in the 1950s, when China built a military road across it to connect Tibet with Xinjiang.^[2]

The 1950s had begun warmly. India and China agreed the Panchsheel, five principles of peaceful coexistence, in 1954.^[5] But India objected to the Chinese presence in Aksai Chin, which it claimed as part of Ladakh, and border skirmishes followed from 1959.^[7]

On 20 October 1962, China's People's Liberation Army attacked across the disputed boundaries. Indian forces were defeated, with 7,000 men killed or captured.^[7] Chinese troops also crossed the McMahon Line into what is now Arunachal Pradesh.^[3] China announced a unilateral ceasefire on 20 November and withdrew from most of the area it had taken, including in the east. It kept about 38,000 square km of Aksai Chin.^[7][3]

Keeping the peace without a line

Relations stayed poor until 1988, when the Indian prime minister Rajiv Gandhi visited Beijing, the first visit by an Indian leader in more than three decades. Both sides agreed to calm the border while working together in other areas.^[5]

On 7 September 1993 they signed an agreement in Beijing. Neither side would use or threaten force, both would keep forces near the line to a minimum, and personnel who crossed it would pull back when cautioned.^[1] The agreement also says that mentioning the line of actual control does not change either side's position on the boundary.^[1]

A second agreement, signed in New Delhi on 29 November 1996, went further. Neither side may open fire, set off blasts or hunt with guns within two kilometres of the line, except on small-arms firing ranges.^[4] Soldiers who come face to face are to “exercise self-restraint”.^[4]

Galwan and after

Stand-offs still happened, at Depsang in 2013, Chumar in 2014 and on the Doklam plateau in 2017.^[5] In April 2020 a larger standoff began in eastern Ladakh, after China moved troops from an exercise in Tibet to near the border.^[8]

On the night of 15 June 2020, soldiers clashed in the Galwan Valley. Twenty Indian soldiers and at least four Chinese soldiers died.^[8] They fought with fists, clubs and stones rather than guns.^[9] These were the first deaths on this border since 1975, and the worst flare-up in more than four decades.^[5]

The two armies pulled back in stages. They left Galwan in July 2020 and both banks of Pangong Tso lake in February 2021. At Gogra–Hot Springs they withdrew in 2021 and 2022.^[8] In October 2024 they agreed on patrolling in two more areas, Depsang and Demchok. Disengagement there began on 22 October.^[8][10] The deal restored patrolling and grazing in those two areas. It did not cover the rest of the border, including Arunachal Pradesh.^[5]