Tibetan Empire

The Tibetan Empire (Tibetan: བོད་ཆེན་པོ, Wylie: bod chen po, lit. 'Great Tibet') was centered on the Tibetan Plateau and formed as a result of expansions under the Yarlung dynasty's 33rd king, Songtsen Gampo, in the 7th century. It expanded further under Trisong Detsen and reached its greatest extent under Tritsuk Detsen, stretching east to Chang'an, west beyond modern Afghanistan, south into modern India and the Bay of Bengal. It is referred to as Tufan or Tubo (吐蕃) in Chinese sources.

The Yarlung dynasty was founded in 127 BC in the Yarlung Valley along the Yarlung River, south of Lhasa. The capital was moved in the 7th century from the Yungbulakang Palace to Lhasa by the 33rd ruler Songtsen Gampo, and into the Red Fort during the imperial period which continued to the 9th century. The beginning of the imperial period is marked in the reign of the 33rd king of the Yarlung dynasty, Songtsen Gampo. Tibet's military power gradually increased over a diverse terrain. During the reign of Trisong Detsen, the empire became more powerful and increased in size. At this time, a 783 treaty between the Tibetan Empire and the Tang dynasty defined the borders, as commemorated by the Shol Potala Pillar in Lhasa. Borders were again confirmed during the later reign of Tritsuk Detsen through his 821–823 treaty, which was inscribed on a pillar at Jokhang. In the opening years of the 9th century, the Tibetan Empire controlled territories extending from the Tarim Basin to the Himalayas and Bengal, and from the Pamirs into what are now the Chinese provinces of Sichuan, Gansu and Yunnan. The murder of Tritsuk Detsen in 838 by his brother Langdarma, and Langdarma's subsequent enthronement followed by his assassination in 842 marks the simultaneous beginning of the dissolution of the empire period.

Before the empire period, sacred Buddhist relics were discovered by the Yarlung dynasty's 28th king, Thothori Nyantsen (lha-tho-tho-ri), and then safeguarded. Later, Tibet marked the advent of its empire period under King Songtsen Gampo, while Buddhism initially spread into Tibet after the king's conversion to Buddhism, and during his pursuits in translating Buddhist texts while also developing the Tibetan language. Under King Trisong Detsen, the empire again expanded as the founding of Tibetan Buddhism and the establishment of the Vajrayana in Tibet by Guru Padmasambhava was occurring.

The empire period then corresponded to the reigns of Tibet's three 'Religious Kings', which includes King Ralpachen's reign. After Ralpachen's murder, King Langdarma nearly destroyed Tibetan Buddhism through his widespread targeting of Nyingma monasteries and monastic practitioners. His undertakings correspond to the subsequent dissolution of the unified empire period, after which semi-autonomous polities of chieftains, minor kings and queens, and those surviving Tibetan Buddhist polities evolved once again into autonomous independent polities, similar to those polities also documented in the Tibetan Empire's nearer frontier region of Do Kham (Amdo and Kham).

Other unreferenced ideas about the dissolution of the empire period include: The varied terrain of the empire and the difficulty of transportation, coupled with the new ideas that came into the empire as a result of its expansion, helped to create stresses and power blocs that were often in competition with the ruler at the center of the empire. Thus, for example, adherents of the Bön religion and the supporters of the ancient noble families gradually came to find themselves in competition with the "recently" introduced Tibetan Buddhism.