Sino-Indian border dispute

The Sino–Indian border dispute is an ongoing territorial dispute over the sovereignty of two relatively large, and several smaller, separated pieces of territory between China and India. The territorial disputes between the two countries stem from the legacy of British colonial-era border agreements, particularly the McMahon Line in the eastern sector, which was drawn in 1914 during the Simla Convention between British-ruled India and Tibet but was rejected by China.

Source: Wikipedia — Sino-Indian border dispute (CC BY-SA 4.0)