Tibet's history prior to the 7th century is obscure with only the archaeological record offering information. From the 7th to the 9th century a line of rulers managed to establish and rule a Tibetan empire. At its prime its rule extended south to Bengal and north to Mongolia. A succession crisis in 842 left Tibet divided into two states, ruled by rival lines of the same dynasty. Further divisions followed over the following centuries. By the early 13th century Tibet had become a "feudal society composed of numerous principalities constantly at war with one another ".
The states of Tibet payed tribute to Genghis Khan (1206 - 1227) but mostly maintained their autonomy. Following the death of the Khan, Tibet stopped paying tribute. The successors of Genghis had other matters and campaigns to attend to, Tibet surviving unnoticed to the 1240s. Two campaigns lasting from 1240 to 1247 unified Tibet under a Viceroy of the Yuan dynasty of China, descendants of Genghis Khan. From 1264 onwards the Regency was hereditary to the leaders of the Sakya monastic school of Buddhism. This period of rule lasted to 1354.
Tai Situ Changchub Gyaltsen, leader of a subordinate monastery, managed to depose the Sakyas and establish his own dynasty, the Phagmodrupa. They ruled unchallenged from 1354 to 1435. They would pay periodic tributes to the Ming dynasty of China. The Ming never interfered with their rule and Chinese influence was mostly nominal for the entirety of the period. The period ended with a civil war. The Phagmodrupa continued ruling part of Tibet to 1565. Another part was ruled by the Rinpungpa dynasty (1435 - 1565).
The decline of the two senior dynasties allowed them to be displaced by two new contenders for power. They were the Tsangpa dynasty (1565 - 1642) and the line of Dali Lamas (1578 - 1642) , monastic leaders of the Gelug sect. In 1642, Gushi Khan, a Mongol ruler, managed to unify Tibet under the nominal authority of Ngawang Lobsang Gyatso, 5th Dali Lama. This long-lived Dali Lama managed to establish his actual authority over the following forty years and initiated the long-term subordination to the Qing Dynasty.
The question of who ruled Tibet between the 1680s and 1912 is often complex. Some Dali Lamas exercised actual authority, others were dominated by Regents or representatives of the Qing. Some Chinese emperors played a great role in Tibetan political events. Others were distant figures of nominal authority. The Qing were deposed in 1912, replaced by a Republic of China. Thubten Gyatso, 13th Dali Lama took advantage to expel all Chinese officials from Tibet. He declared Tibet a sovereign nation in 1913.
Tibet received limited international recognition and its status was questioned by China. But a series of internal conflicts and civil wars prevented China from acting against it. Japan was attempting to annex areas of China but its influence never extended to Tibet. Tibet became a relatively isolated area and the 13th Dali Lama continued ruling to his death in 1933. Tibet did not participate in World War II, though it did congratulate China and India over their combined victory in 1946. India recognized it as a sovereign state in 1947.
By 1950, the Chinese Civil War had effectively ended and a People's Republic of China established. In October, 1950, the People's Liberation Army invaded and occupied Tibet. In 1951, it was formally annexed to the People's Republic. However Tenzin Gyatso, 14th Dali Lama remained in position as a de facto subordinate ruler and there were few actual changes in the 1950s. An Uprising against Chinese rule in 1959 backfired. The Dali Lama and several of his supporters were forced into self-exile. China declared Tibet to be a Special Territory. While a Tibetan Lama is always the nominal leader, actual decisions are taken by Communist Party officials. Meanwhile the exiles have created a Tibetan independence movement with a wide-spread influence by the 21st century. The status of Tibet remains controversial.