McMahon Line and the Simla Convention

The McMahon Line is the boundary alignment India recognises between Arunachal Pradesh and Tibet in the Eastern Sector. It emerged from British-Tibetan negotiations during the Simla Conference of 1913-14, but was not a boundary settlement finally accepted by all three participants: British India, Tibet and China.

The Simla negotiations

The conference sought to settle Tibet's political status and its boundaries. Sir Henry McMahon, the British representative, also negotiated the boundary between British India and Tibet with the Tibetan delegation.

• The proposed convention distinguished Inner Tibet and Outer Tibet, envisaging Chinese suzerainty over Tibet alongside autonomy for Outer Tibet.
• Two boundary questions must be distinguished: the division between Inner and Outer Tibet, and the India-Tibet boundary that became known as the McMahon Line.

How the boundary line was recorded

The decisive India-Tibet boundary arrangement was recorded through letters exchanged on 24-25 March 1914 between McMahon and the Tibetan representative, together with an accompanying map. Thus, the line originated in a bilateral understanding reached within the wider Simla negotiations.

• The mapped alignment broadly followed the Himalayan watershed, separating the Tibetan plateau from the southern Himalayan slopes.
• It placed Tawang south of the line, on the British Indian side of the proposed boundary.
• The arrangement was a diplomatic delimitation, meaning that the boundary was described and mapped; this did not itself amount to continuous physical demarcation on the ground.

Why the convention did not settle the dispute

The Chinese representative initialled the draft convention in April 1914, but the Chinese government withheld acceptance. British and Tibetan representatives signed the convention on 3 July 1914, alongside a declaration proceeding without China's adherence.

• China's refusal to accept the convention centred on the proposed Inner Tibet-Outer Tibet boundary; it should not be confused with Chinese acceptance of the separate India-Tibet alignment.
• India treats the McMahon Line as the settled boundary inherited from British India.
• China rejects the line and disputes Tibet's authority to conclude such an agreement independently, leaving the Eastern Sector boundary contested.