Following collapse of the Manchu dynasty in 1911, China was determined to unify Tibet as a province. When Tibet used the weakening of central government control to declare independence in 1913, this was not matched by any constitutive independence. Dalai Lama’s government lacked stability and recognition.
Britain, specifically Henry McMahon, then foreign secretary to British India, had an interest in using this opportunity to secure a buffer between China and India. So when Tibet approached Britain for assistance to secure its boundaries from Chinese interference, the latter readily obliged by threatening China with the consequence of separately negotiating with Tibet.
In 1913, the British convoked a conference at Simla, India to discuss the issue of Tibet’s status. The conference was attended by representatives of Britain, the newly founded Republic of China, and the Tibetan government at Lhasa.
China agreed to negotiate settlement of Tibetan affairs under this ‘tripartite’ arrangement and Chen I-fen was appointed to represent China, McMahon was appointed to represent Britain, and Longchen Shatra (‘prime minister’ of Tibet) was nominated by Dalai Lama.
In conclusion, several coloured lines drawn on a small-scale map (a modified Royal Geographical Society map of 1906) by the parties themselves – yellow claim lines by the Chinese, green by Tibet, blue and red for “inner” and “outer” Tibet respectively. On April 27, 1914 the draft of the convention was initialled by Shatra, McMahon and Chen.
What is curious, however, is that despite the three plenipotentiaries deliberating on the limits of Tibet until early July 1914, two other maps (along with exchange of notes) had been separately signed between Britain and Tibet earlier in March.
Unlike the small-scale tripartite convention map, these were large-scale maps, signed on March 24, 1914 in Delhi (away from Simla) by the British and Tibetan plenipotentiaries. Chen was not part of the process of negotiating claim lines on these large-scale maps.
Moreover, it defined the Indian boundary north of Tawang, unlike in the convention map of July 3, 1914 that had a thick red line inked over Tawang and running along the crest of the Himalayas north-eastwards, bringing present-day Arunachal Pradesh within Indian limits.
On March 24, 1914 itself finality had been assumed by Britain and Tibet on the crucial matter of the boundary and the ‘McMahon Line’ was born even before the draft Simla convention was initialled in April.