McMahon Line
Months after the Simla agreement, China set up boundary markers south of the McMahon Line. T. O'Callaghan, an official in the Eastern Sector of the North East Frontier, relocated all these markers to a location slightly south of the McMahon Line, and then visited Rima to confirm with Tibetan officials that there was no Chinese influence in the area. The British-run Government of India initially rejected the Simla Agreement as incompatible with the Anglo-Russian Convention of 1907, which stipulated that neither party was to negotiate with Tibet "except through the intermediary of the Chinese government". The British and Russians cancelled the 1907 agreement by joint consent in 1921. It was not until the late 1930s that the British started to use the McMahon Line on official maps of the region.