The British convened a tripartite conference to discuss Tibet's status at Simla in 1914. The Tibetans arrived at the conference with written evidence proving the historical independence of Tibet. The Chinese delegation, who were present only to witness the treaty between Britain and Tibet, argued that Tibet's subjugation by the Mongols and the Manchus proved it had become an integral part of China, and should therefore now be ruled as part of the new Republic of China of Sun Yat Sen from Peking. However, Tibet was not really subjugated by the Mongols and Manchus but influenced by them. Neither Mongols nor Manchus were Chinese. In fact China itself was occupied for long by both the Mongols and the Manchus.
Using the same argument India can claim Burma, Malaysia, Singapore, HongKong as well.