Sino-Tibetan War (1930-1932)

1930-1932 Sino-Tibetan War - A Tibetan army attacked Sichuan Province in China, which was then ruled by a warlord named Liu W en-Hui. China was at the time divided among dozens of "Warlords" who often fought among themselves as well as against the central Chinese government. Liu Wen-Hui battled the Tibetans for several years, sometimes with the aid of other warlords, such as the Qinghai province's warlord Ma Bu-Fang. A peace agreement was finally signed in 1932, setting Tibet's eastern border at the Yangtse River.  Actually, the Tibetans were forced back. The treaty from 1932 said that not the Yantse river but the Jinsha river would be the border. This borderline in general corresponded to the border between the "Inner" and "Outer" Tibet, as it was stipulated during the Simla-conference in 1914. 

The Picture shows the border between Lhasa-controlled ("Outer Tibet") and Chinese-controlled ("Inner Tibet") regions in Kham, 1912–1945. The dark blue line represents the boundary proposed in the 1914 Simla Convention and the red line the overall boundary of Tibet. The remaining lines represent actual control: the dotted blue line up to 1910; the light blue line during 1912–1917; and the dark brown line during 1918–1932.