The McMahon Line is the boundary: "The main British gain from the Simla Conference was the delimitation of the McMahon Line, the boundary along the crest of the Assam Himalayas from Bhutan to Burma, by means of an exchange of Anglo-Tibetan notes." between Tibet and British India as agreed in the maps and notes exchanged by the respective plenipotentiaries on 24–25 March 1914 at Delhi,: "To give their agreement shape and form, McMahon and Lonchen exchanged formal letters and copies of maps showing the boundary. This was done at Delhi on 24–25 March." as part of the 1914 Simla Convention. The line delimited the respective spheres of influence of the two countries in the eastern Himalayan region along northeast India and northern Burma (Myanmar), which were earlier undefined.: Quoting Lord Crew, British Secretary of State for India: "that by a definition of the boundary between Tibet and India he (Crewe) understands the Government of India to mean an agreement as to the spheres, at present undefined, of the two countries in the tribal territory east of Bhutan": "there was no intention of 'administering' the country 'within the proposed frontier line much less of undertaking 'military operations' in the area in question. And yet,... it was desirable 'to maintain some semblance of authority that could be backed by force, 'if necessary'." The Republic of China was not a party to the McMahon Line agreement, but the line was part of the overall boundary of Tibet defined in the Simla Convention, initialled by all three parties and later repudiated by the government of China.: 'The McMahon Line (ML), shown by a Red line on the 1914 map, was an integral part of a longer, more comprehensive line drawn on the convention map to illustrate Article IX thereof... The map is initialled by the three plenipotentiaries 'in token of acceptance" on "this 27th day of April 1914".' The Indian part of the Line currently serves as the de facto boundary between China and India, although its legal status is disputed by the People's Republic of China. The Burmese part of the Line was renegotiated by the People's Republic of China and Myanmar.
The line is named after Henry McMahon, foreign secretary of British India and the chief British negotiator of the conference at Simla. The bilateral agreement between Tibet and Britain was signed by McMahon on behalf of the British government and Lonchen Shatra on behalf of the Tibetan government. It spans from the corner of Bhutan to the Isu Razi Pass on the Burma border, largely along the crest of the Himalayas.: "In negotiating a boundary between British India and Tibet, the line was drawn to include Burma as far east as the Isu Razi pass, south of the Taron River near the Irrawaddy-Salween watershed."
The outcomes of the Simla Conference remained ambiguous for several decades because China did not sign the overall Convention but the British were hopeful of persuading the Chinese. The Convention and the McMahon's agreement were omitted in the 1928 edition of Aitchison's Treaties.: "for nearly two decades after 1914, the dubious risk of attracting Russian, and later Chinese, attention continued to be the principal reason for the non-publication of the Simla Convention and its adjuncts, the Trade Regulations and the India Tibet boundary agreement." It was revived in 1935 by Olaf Caroe, then deputy foreign secretary of British India, who obtained London's permission to implement it as well as to publish a revised version of Aitchison's 1928 Treaties. Since then the McMahon Line has been part of the legal national border of India.
China rejects the Simla Convention and the McMahon Line, contending that Tibet was not a sovereign state and therefore did not have the power to conclude treaties. However China recognizes the line as part of the Line of Actual Control between the two countries, according to a 1959 diplomatic note by Prime Minister Zhou Enlai. Chinese maps show some of the territory south of the line as part of the Tibet Autonomous Region, known as South Tibet in China. Chinese forces briefly occupied a part of this area during the Sino-Indian War of 1962 and later withdrew.
The 14th Dalai Lama did not originally recognise India's sovereignty over Arunachal Pradesh. As late as 2003, he said that "Arunachal Pradesh was actually part of Tibet". In January 2007, however, he said that both the Tibetan government and Britain recognized the McMahon Line in 1914. In June 2008, he explicitly recognized for the first time that "Arunachal Pradesh was a part of India under the agreement signed by Tibetan and British representatives".
Background
British India expanded east of Bhutan in the early 19th century with the First Anglo-Burmese War. At the end of the war, the Brahmaputra valley of Assam came under its control, and over the next few decades, under its direct administration. The thickly forested hill tracts surrounding the valley, constituting the present-day Arunachal Pradesh, were inhabited by tribal people, who were not easily amenable to British administrative control. The British were content to leave them alone. In 1873, the British drew an "Inner Line" as an administrative line between the directly-administered territory and the tribal territory, and British subjects were prohibited from passing into the latter without explicit permission.: ".. with the growth of commercial interests (mainly tea plantation and Umber), in the second half of the nineteenth century, the British Government became apprehensive of uncontrolled expansion of commercial activities by British merchants, because that could bring them into conflict with the tribal people. To prevent that possibility, the government decided, in 1873, to draw a line—the 'Inner Line'—that could not be crossed without a proper permit.": "The tribal peoples, notably the Abors, Daflas, Mishmis, Monpas, Akas and Miris, apart from some occasional episodes of subordination to Assam or Tibet, were for all practical purposes independent."
The British boundary, also called the "Outer Line", was defined to mark the limits of British jurisdiction. But it was not significantly different from the Inner Line in this region.: "It [the Outer Line] followed the line of 'the foot of the hills' a few miles to the north of what became the course of the Inner Line."
The British wanted peaceful relations with the Himalayan tribes who lived beyond the Inner Line.: Quoting Lord Curzon, the Viceroy of India, from 1905: "We do not want Mr (J C) White or anybody else to present us with a North-east frontier problem or policy. There being no problem beyond that of remaining on peaceful and friendly terms with our neighbours and quietly developing our relations ... there is no occasion for a policy." However, British influence was nevertheless extended to many regions, through treaties, trade relations, and occasional punitive expeditions in response to "outrages" committed against British civilians.: "These British expeditions often came into conflict with the tribal people living in the hill tracts and retaliated with punitive measures.... These punitive expeditions beyond the Outer Line gradually extended British political control to areas that were later to be incorporated into the North East Frontier Agency (NEFA).": "While the tribal hills were not inside the limits of British territory, yet it was felt that they fell within the sphere of British influence, and that the Indian Government was fully entitled to take what action it saw fit there to protect its interests. There seemed no need, however, before 1910 to have this situation confirmed by any international agreement." There is evidence that the British regarded the Assam Himalayan region as a geographical part of India irrespective of political jurisdiction. Guyot-Réchard sees them as having extended "external sovereignty" over the Assam Himalayan tribes.: "Delhi and London's vision followed an imperial logic: the eastern Himalayas should be a buffer between India and its neighbourhood. Confronted by Chinese expansionism, their aim was limited to achieving external sovereignty over the region – that is, to ensure that no foreign power would intrude into the eastern Himalayas, and that local people would have 'no relations or intercourse with any Foreign Power other than the British Government'."
Forward policies of early 1900s By 1900, Chinese influence over Tibet had significantly weakened and the British became apprehensive that Tibet would fall into a Russian orbit. In an effort to preclude Russian influence over Tibet and to enforce their treaty rights, the British launched an expedition to Tibet in 1904, which resulted in the Convention of Lhasa between Tibet and Britain.
Qing China became apprehensive about British inroads into Tibet and responded with its own forward policy. They took complete control over the southeastern Kham region of Tibet (also referred to as the "March Country"), through which passed the Chinese communications to Tibet. An assistant amban (imperial resident) was appointed for Chamdo in western Kham to implement the new strategy. Over a period of three years, 1908–1911, the amban Zhao Erfeng implemented brutal policies of subjugation and sinification in the Kham region, for which he earned the nickname of "Zhao the Butcher" (Chinese: 趙屠戶).
Zhao Erfeng's campaigns entered the Tibetan districts adjoining the Assam Himalayan region such as Zayul, Pomed (Bome County) and Pemako (Medog County). They also encroached into parts of the adjoining tribal territory and attempted to exert influence. This alarmed British officials in the region, who advocated the extension of British jurisdiction into tribal territory.: "Mounting Chinese activity in the Assam Himalaya (1907-11) invited reactions in terms of explorations by the British culminating in the Abor expedition (1911), the Mishmi and Miri missions, the Aka and Walong promenades (1911-12) and the Bailey-Moreshead explorations (1913-14) around Tawang.": "When China attempted to reassert control over Tibet around 1910 her troops penetrated into the Walong area and placed boundary markers there. Appreciative of the danger of further encroachment, the governor of Assam in 1910 advised the Viceroy to press forward beyond the limits which "under a self-denying ordinance" contained the frontier." The higher administration of British India was initially reluctant to concede these demands, but, by 1912, the Army General Staff had proposed drawing a boundary along the crest of Himalayas.: "All in all, the frontier line proposed by the Army top brass from west to east, was to follow the watersheds of the Subansiri, with its tributaries the Kamala and the Khru, the Dihang as far as its major gorge and all its tributaries south of that point, the Dibang and its confluents and the Lohit and its tributaries. The proposed line, it was pointed out, 'corresponded very closely' with the one suggested by the Government of India in its letter of 1911." The British appear to have been clear that they were only extending the political administration of their rule but not the geographical extent of India, which was taken to include the Assam Himalayan region.: Quoting the Secretary of State for India in 1913, "It should be observed that Tibet is nowhere coterminous with the settled districts of British India, but with a belt of country which, though geographically part of India, politically is partly a no-man's land inhabited by aboriginal savages, partly the territories of states [Nepal, Bhutan and Sikkim] ...." (emphasis added)
Tawang tract