The Bon religion, the primitive religion of the ancient Tibetans, was flourish before the introduction of Buddhism. Its priests were powerful both militarily and economically, wielding control even over the nobility. In the 7th century, Songtsan Gambo (?-650) unified the Tibetan Plateau and established the Tubo Kingdom. Defying the Bon priests, he introduced Buddhism into Tibet. He married Princess Bhributi from Nepal, who brought a life-sized statue of Sakyamuni at the age of eight, and then married Princess Wencheng of the Tang Dynasty (618-907), who brought a life-sized statue of Sakyamuni at the age of 12, as well as 360 volumes of Buddhist sutras as her dowry. From then on, the civilization of the Central Plains of China started to flow into Tibet. Songtsan Gambo also constructed the Jokhang and Ramqe monasteries in the capital, Lhasa.

The following 100 years saw incessant conflicts between Buddhism and Bon. The latter half of the 8th century saw the construction of the Samyai Monastery, the first large-scale Buddhist monastery in Tibet. By the early 9th century, more monasteries were constructed, and the influence of Buddhism in Tibet reached its zenith.

However, internal strife ripped apart the royal house, and in the five years (838-842) of the reign of King Darma, the Bon religion revived; during the following 100 years, Tibetan Buddhism became almost extinct. By the end of the 10th century, Buddhism had become popular again, but it was divided into many sects, reflecting political loyalties. The leading sects included the Nyingma Sect (Red Sect), Sagya Sect (Flower Sect), Kagdams Sect, Kabrgyud Sect (White Sect), and Gelug Sect (Yellow Sect). Historians classify the period from the reign of Songtsan Gambo to that of Darma as the "Early Period of Buddhism, and the period of the renaissance of Buddhism and the emergence of the sects the "Later Period of Buddhism"

MONKS
There are about 500 tulkus/living Buddhas in Tibet. In some monasteries, there are several tulkus. The lineage usually starts by some legend or a decree of the Emperor or King. The reincarnation of a tulku/living Buddha was originally determined by oracles, and later, by a royal decree, determined by the Lottery System. Sometimes, the Emperor or local Tibetan government prohibits the continuation of some lineages. For instance, the lineage of tulku Radreng is a good example. The monastery Radreng was built in 1056 as the Principal Monastery of Ka-dams-pa (Old Yellow Hat sect). Late it became a monastery of Ge-lug pa (Yellow Hat sect). In 1862, Radreng was the regent of Tibet and was accused taking bribery by his political oponents. Losing the struggle, he run to the central government in Beijing with the seal of the regent. The central government judged him guilty, terminated the lineage of tulku Radreng (i.e., prohibit him to reincarnate), and gave the Radreng Monastery to Dalai Lama. After his passage in 1863, the central government reversed herself in 1877, and proclaimed him innocent, reestablished the lineage of Radreng, restored the Radreng Monastery to the control of the reincarnation of that lineage. Later the Tibetan government terminated Radreng lineage in 1947 after the new Radreng was forced to resign from his regentship and after further political warfare.

Monk Student Life
Usually, only adult males become students. However, sometimes, young boys joint the monasteries. For the first year the novice supports himself as he studies in a preparatory class at a `dratsang' of exoteric Buddhism. Study begins with the Tibetan alphabet and moves on to the common prayers. After passing examinations at the end of the first year he qualifies as a regular student for the study of esoteric Buddhism. Still lying before him is an extended period of studying lasting from ten to twenty years, during which time he is expected to master in thirteen successive stages five Buddhist scriptures: the Hetuvidya, the Prajna, the Pranyamula-sastra-tika, the Sila and Vinaya and Abhidharma-kosa-sastra.

Upon completing these courses and with the recommendation of his tutor and the approval of the monastery's authorities, the student monk may apply to take qualifying tests, given either in the form of debate or oral test, for `geshi' degree. Very few monks pass the tests. The degree of `geshi' qualifies a holder for the position of `khenpo', and to continue his study at a higher level in the `dratsang' of esoteric Buddism. As a rule, the tulkus/living Buddhas hold the `geshi' degrees. The degree system is similar to Han people's three levels degree system.

Lama
The term `lama', meaning `guru' or master in Tibetan, used to be the tittle reserved solely for high-ranking or accomplished Tibetan Buddhist monk, ordinary monks were merely `drapas'. Later, as `lama' came to be used as a polite form od address for any `drapa', it became a common misnomer for all Tibetan monks.