Buddhism had reached the Tibetan court before Trisong Detsen, but as a foreign practice patronized by particular queens and ministers rather than as the religion of the realm, and it had powerful opponents among the nobility and among the priests of the older Tibetan cult. Trisong Detsen made it official. He invited Santaraksita, an abbot and philosopher from the Indian monastic university tradition, whose first stay ran into resistance and a run of disasters that were blamed on offended local spirits. On Santaraksita's advice the emperor then invited Padmasambhava, a tantric master whose reputation was for subduing exactly such powers, and Tibetan tradition holds that he bound the local deities by oath to protect the new religion rather than destroying them.
Samye was built with that settlement behind it, on a plan representing the Buddhist cosmos with Mount Meru at the centre and the continents around it, and consecrated in about 779. It was the first monastery in Tibet, and its purpose was to make Buddhism reproducible without further imports: seven Tibetan men were ordained there as monks, known in the histories as the seven men to be tested, and once ordination existed inside Tibet the tradition could continue on its own.
The other institution founded in the same reign was the translation office. Trisong Detsen funded teams of Indian scholars working with Tibetan translators, and the standardization of Buddhist vocabulary in Tibetan begins here, producing eventually one of the most complete surviving records of Indian Buddhist literature, much of it preserved in Tibetan after the Sanskrit originals were lost.