The British expedition to Tibet, also known as the Younghusband expedition, began in December 1903 and lasted until September 1904. The expedition was effectively a temporary invasion by British Indian Armed Forces under the auspices of the Tibet Frontier Commission, whose purported mission was to establish diplomatic relations and resolve the dispute over the border between Tibet and Sikkim. In the nineteenth century, the British had conquered Burma and Sikkim, with the whole southern flank of Tibet coming under the control of the British Indian Empire. Tibet was ruled by the 13th Dalai Lama under the Ganden Phodrang government as a Himalayan state under the protectorate of the Chinese Qing dynasty until the 1911 Revolution, after which a period of de facto Tibetan independence (1912–1951) followed.