Trisong Detsen in the context of "Testament of Ba"

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.

Nyingma (Tibetan: རྙིང་མ་, Wylie: rnying ma, Lhasa dialect: [ɲ̟iŋ˥˥.ma˥˥], lit. 'old school'), also referred to as Ngagyur (Tibetan: སྔ་འགྱུར་རྙིང་མ།, Wylie: snga 'gyur rnying ma, Lhasa dialect: [ŋa˥˥.ʈ͡ʂuɹ], lit. 'order of the ancient translations'), is the oldest of the four major schools of Tibetan Buddhism. The Nyingma school was founded by Padmasambhava as the first translations of Buddhist scriptures from Pali and Sanskrit into Tibetan occurred in the eighth century. The establishment of Tibetan Buddhism and the Nyingma tradition is collectively ascribed to Khenpo Shantarakshita, Guru Padmasambhava, and King Trisong Detsen, known as Khen Lop Chos Sum (The Three: Khenpo, Lopon, Chosgyal).

The Nyingma tradition traces its Dzogchen lineage from the first Buddha Samantabhadra to Garab Dorje, and its other lineages from Indian mahasiddhas such as Sri Singha and Jnanasutra. Yeshe Tsogyal recorded the teachings. Other great masters from the founding period include Vimalamitra, Vairotsana, and Buddhaguhya. The Nyingma tradition was physically founded at Samye, the first monastery in Tibet. Nyingma teachings are also known for having been passed down through networks of lay practitioners, and of Ngakmapas (Skt. mantrī).

Padmasambhava ('Born from a Lotus'), also known as Guru Rinpoche ('Precious Guru'), was a semi-legendary tantric Buddhist Vajra master from medieval India, who according to hagiographical sources fully revealed the Vajrayana in Tibet, circa 8th – 9th centuries. He is considered an emanation or Nirmāṇakāya of Shakyamuni Buddha as foretold by the Buddha himself. According to early Tibetan sources including the Testament of Ba, he came to Tibet in the 8th century and designed Samye Monastery, the first Buddhist monastery in Tibet during the reign of King Trisong Detsen. He, the king, and Khenpo Shantarakshita are also responsible for creating the Tibetan Canon through translating all of the Buddha's teachings and their commentaries into the Tibetan language.

According to Lewis Doney, while his historical authenticity was questioned by earlier Tibetologists, it is now "cautiously accepted.” Padmasambhava himself was recorded as saying he was a historical person, and his footprints left in rocks are evidence. Padmasambhava later came to be viewed as a central figure in the transmission of Buddhism to Tibet. Starting from around the 12th century, hagiographies concerning Padmasambhava were written. These works expanded the profile and activities of Padmasambhava, now seen as taming all the Tibetan spirits and gods, and concealing various secret texts (terma) for future tertöns. Nyangral Nyima Özer (1124–1192) was the author of the Zangling-ma (Jeweled Rosary), the earliest biography of Padmasambhava. He has been called "one of the main architects of the Padmasambhava mythos – who first linked Padmasambhava to the Great Perfection in a high-profile manner."