First of all it is NOT McMohan line. Nothing to do with Mohan, or Krishan etc.
The correct version is The McMahon Line, named after Sir Henry McMahon, foreign secretary for the British-run Government of India and the chief British negotiator of the convention which drew the demarcation line drawn on map referred to in the Simla Accord, a treaty between Britain and Tibet signed in 1914 at the end of the Simla Convention.
Although its legal status is disputed, it is currently the effective boundary between China and India.
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McMahon Line marks the international boundary between Tibet and India in the eastern Himalayan region. The McMohan Line is also a demarcation line drawn on the map referred to the Simla Convention, a treaty between Britain and Tibet signed in 1914. This line is named after Sir Henry McMahon, foreign secretary for the British-run Government of India and the chief British negotiator of the convention. The McMahon Line is regarded by India as a legal national border. The Dalai Lamas Tibetan government-in-exile also accepts the line as an official border. China rejects the Simla Convention on the grounds that the Tibetan government was not sovereign and therefore did not have the power to conclude treaties. Strangely, China does not dispute the international border with Burma that was also drawn as part of the McMahon Line! The line was the focus of a brief war in 1962 between China and India. On October 20, 1962 China launched a major attack across the McMahon as well as another attack fu