Songtsen Gampo in the context of "Tibetan script"

The Yarlung dynasty (Tibetan: བོད་ཀྱི་གདོད་མའི་མངའ་མཛད།) was a Tibetan dynasty that existed from 127 BCE to 842 CE. It produced 42 rulers and gave rise to the Tibetan Empire period from 614 CE to 848 CE, credited to the 33rd monarch Songtsen Gampo, and lasting through to the 40th monarch Ralpachen. Ralpachen was murdered in 838 by his brother, the future 41st monarch Ü Dum Tsen, who in turn ruled for only one year (841–842) until his own murder. The dissolution of the empire occurred by 848.

The early Yarlung dynasty rulers lived before the Tibetan script was created, and their reigns and lives were documented through the lineage of verbal history until c. 650 when in the reign of the 33rd king of the Yarlung Dynasty Songtsen Gampo, the Tibetan alphabet and grammar were created and the royal record keeping of people and events called the Chronicle of Ba began. While some scholars feel unsure of the definitive existence due to the lack of written records before 650, the verbal lineage of Tibetan history is considered definitive for most scholars.

The Tibetan Empire, or the Empire of Tibet (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 Ralpachen, 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 Yarlung 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 ruler of the Yarlung dynasty, Songtsen Gampo. The power of Tibet's military empire 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 the 40th king Ralpachen 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 King Ralpachen 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.

Trisong Detsen (Tibetan: ཁྲི་སྲོང་ལྡེ་བཙན, Wylie: khri srong lde brtsan/btsan, ZWPY: Chisong Dêzän, Lhasa dialect: [ʈʂʰisoŋ tetsɛ̃]) was the son of Me Agtsom, the 37th king of Tibet. As the 38th king, he ruled from AD 755 until 797. Trisong Detsen was the second of the Three Dharma Kings of Tibet — Songtsen Gampo, Trisong Detsen, Rapalchen — honored for their pivotal roles in the introduction of Buddhism to Tibet and the establishment of the Nyingma or "Ancient" school of Tibetan Buddhism. Sowa Rigpa or Traditional Tibetan medicine was developed during his reign.

Trisong Detsen became one of Tibet's greatest kings during its empire era, and an unparalleled Buddhist benefactor to Guru Padmasambhava, to Khenpo Shantarakshita, to his court, and to the founding of the Vajrayana. By the end of his reign, he grew the extents of Tibet beyond their previous borders, reset the borders between Tibet and China in 783, and even occupied the capital of China at Chang'an, where he installed a king.