Buddhism played an important role in the history of Tubo kingdom. As early as the time of King Songtsan Gambo, statues of Buddha had been introduced. Later, there were intense struggles over whether Buddhism was allowed to be promoted.

After Trisung Detsan came to the throne, he eliminated ministers opposed to Buddhism. He also invited from India the Abbot Santaraksita and the Guru Padmasambhava, heralding a new era of promoting Buddhism on a large scale. In order to advocate Buddhism in Tubo, Guru Padmasambhava adopted the spirits of mountains, lakes, and dragons, which had been believed since Tubo prehistory into the spiritual system of the Buddhist Mahayana on the basis of the theory of worldly deities of Buddhism. Thus, a set of religious rituals of sacrifices and offerings were set up. From 767 to 779, the Samye Monastery, the first formal monastery in Tubo was built and the First Seven Buddhist Monks fully ordained, laying a foundation for the development of Tibetan Buddhism in Tubo that enjoyed great support from King Trisung Detsan and his son, Moni Tsampo, who were devoted believers. The king contributed to the expenses of the monasteries and Buddhist monks, from tax imposed on ministers and the populace. At the same time, every monastery and Buddhist monk were under the strict control of the royal court. In order to administer Buddhist affairs, special officials were appointed. Later, King Trisung Detsan conferred on Ding’eizenwei, his Buddhist teacher in childhood, the position of Boshanbo and huge lands and subjects as his personal property. Ding’eizenwei was the second only to the emperor, and he was in charge of military and political affairs, so was also known as Buddist Prime Minister.

In 815, when King Tride Songtsan was succeeded by his son Ralpachen, the cause of Buddhism was further promoted. They made great efforts to build monasteries, accept more Buddhist monks and translate on a large scale the Buddhist classics. The large quantity of delicate Buddhist scriptures of Tibetan edition kept in Dunhuang was second only to that of Chinese edition in terms quantity, and were rare cultural relics. In addition, King Ralpachen ordered that every seventh household should support a Buddhist monk, making the latter into a special class enjoying privileges. Laws also protected these privileges, and if one dared to express any dissatisfaction toward Buddhist monks, he would face severe punishment. As a result, the resentment toward Buddhist monks and the ruling class was so intense that it led to the assassination of King Ralpachen in 841 by factions opposed to Tibetan Buddhism. Lang Darma, King Ralpachen’s brother, was supported as the successor. In 843, he blamed Tibetan Buddhism and took many steps to prosecute Buddhist monks and their monasteries, leaders of Tibetan Buddhism were killed, while monks were forced to resume secular life; monasteries were ordered to close and statues of Buddha as well as Buddhist scriptures were destroyed. But this failed to ease the social contradictions, and actually stirred up stern opposition of Buddhist monks. In 846, King Lang Darma was shot to death by the Buddhist monk Lhalhung Beigye Dorgye.