The previous period of Buddhism is an important period in the history of the Tibetan Buddhism.

The Tibet King Trisong Detsen was a believer of Buddhism in the 8^th century. In order to spread Buddhism, he invited Santarakshita and Padmasambhava, two Buddhism masters in India, to promote Buddhism in Tibet (referred to as the Tufan in ancient times). After their arrival, they began to establish the base of Buddhism, and the first monastery, Samye Monastery, was thus constructed for tonsured monks. After the establishment of the Samye Monastery, Trisong Detsen specially dispatched people to India to invite 12 monks to hold the ceremonies of tonsure and commandment for seven young aristocratic Tibetans. This was an extremely important event in the history of the Tibetan Buddhism.

After King Tritsug Detsen Ralpachen ascended the throne in Tibet at the beginning of the 9^th century, he ordered his people to translate a lot of Buddhist canons with the amount exceeding that had been finished by the Han Nationality. He also stipulated that every seven families should sustain one monk's life and monks were allowed to take part in events and issues of the court. Buddhism was therefore thriving thanks to the support of the Tibetan king.

However, the measures of King Tritsug Detsen Ralpachen gained no popularity and favor among the aristocrats and the common people. Before long, the aristocrats plotted to murder King Tritsug Detsen Ralpachen, and a large-scale campaign was carried out against the Buddhism. The Samye Monastery and other famous monasteries were closed, and monks were forced to believe in Bon Religion, a local religion in Tibet. This Buddhism-banning campaign heavily attacked Buddhism, so the period of about 100 years after the Lang Darma was called Buddhism Destructing Period, and the period from the reign of King Srongtsen Gampo, when Buddhism was introduced into Tibet, to the Lang Darma reign was called the Anterior Propagating Period of Buddhism in the history of Tibetan Buddhism.