During Tibet's history, it has existed as a region of separate sovereign areas, a single independent entity and as a part of successive Chinese dynasties. Tibet was first unified under King Songtsän Gampo in the 7th century. At various times from the 1640s until 1950s, a government nominally headed by the Dalai Lamas, a line of spiritual leaders, ruled a large portion of the Tibetan region. During most of this period, the Tibetan administration was subordinate to the Chinese empire of the Qing Dynasty.
In 1913 the 13th Dalai Lama expelled Qing's representatives and troops from what is now the Tibet Autonomous Region. While the expulsion was seen as an assertion of Tibetan autonomy, Tibet's proclaimed independence was not accepted by the government of China, nor did Tibet receive foreign diplomatic recognition.
Following a decisive battle at Chamdo in 1950, the Communist Party of China gained control of the region of Kham to the West of the Upper Yangtze River. The next year the 14th Dalai Lama and his government signed the Seventeen Point Agreement. In 1959, he together with a group of Tibetan leaders and followers fled to India and set up the Government of Tibet in Exile in Dharamshala. Beijing and the Government-in-exile disagree over when Tibet became a part of China, and whether the incorporation into China of Tibet is legitimate according to international law. Since what constitutes Tibet is a matter of much debate (see map, right), neither its size nor population are simple matters of fact, due to various entities claiming differing areas as part of "Tibet".