Buddhism emergence in Tibet was much paradoxical, but in many reference it said the first official introduction of a Buddhist scripture into Tibet happened during reign of 28th Yarlung king Lhatho Thori Nyantsen,(around 500 CE), however, the book was not translated at the time.
Then later the 33rd King of Tibet, Song Tsen Gampo (born 617) had translated it, More over the king Songtsen Gampo married for two wives from alliances with neighbouring powers. One came from Nepal, the other from China; both are Buddhist and both broung with them precious Buddhist images as a part of their dowry, then later they built temples in Lhasa to house their Buddha images, so that the Jokhang temple was built by Princess Brikuti(Nepalese prince) and Ramoche temple was built by Prince Wencheng (Chinese prince), it is the first visible foothold of Buddhism in Tibet. But it is not until the second half of the 8th century that Tibetan kings actively promote Buddhism as their state cult. It is the 38th King of Tibet, Trisong Detsen(in some histoy book it said he was 37th King of Tibet) invited Indian Pandit Shantarakshita and Kamalasila, who suggested to invite Padmasambhava (or Guru-Rinpoche) to Tibet when they were failed to build the Samye monastery against the Bon objection.
An ordained spiritual community was established in the first Buddhist monastery; Samye, which was built by Padmasambhava. In this period, translation of scriptures genuinely began. At that time numbers of Indian scholars invited to Tibet and Buddhism canons were translated into Tibetan, apart from that Guru Padmasambhava had controlled the rebellion from the Bon believers at the same time. So all these contributed to the firmly establishment of Buddhism in Tibet, as the presence of Sangha is considered essential.
In 792, after a great philosophical debate, King Trisong Detsen officially declared Indian Buddhism to be the state religion of Tibet, not the Chinese Buddhism who was failed in debate.
A magician originating in Hindhukush Padma-sambava introduced deeper the tantric doctrines of Mahayana. On this occasion, the problem was of implementing the occult forces (or magic existing rituals) to ensure the deliverance and to avoid the infinite succession of rebirths. One could use the methods of the shamanism, but with new objectives. Padma-sambava succeeded in modifying the Tibetan faith after having triumphed over all the magicians Bon-Po, whom he defeated one after the other. Under his impulse, the large temple of Samye was built in 12 years (towards 775) taking as model an Indian temple (perhaps that of Nalanda). He erected many temples between Lhasa and the valley of Yarlung, moreover, he left his foot prints everywhere in Tibet and hundreds of meditating caves within the country is believed to be blessed by his attendance, those hermitages and caves are still can be visited and functioning by local Yogis and meditators.
Deline and revival
Buddhism almost disappeared after 842 when King Lang Darma violently persecuted Buddhism. After this, for a long time there were no ordinations and no central religious authority in Tibet. Instead, the original Bon religion prevailed.
In 978, with the introduction of several Indian Pandits and Tibetan monks studying in India, Buddhism revived, with the help of king Yeshe O from Guge Kingdom. A real revival occurred after 1042, when Atisha-di-Pankhara (or Jo Je Palden Atisha) put Tibetans “back on the right track”.
He presented the Buddhist philosophy in a very clear and condensed manner, which became the basis for philosophical teachings in most Tibetan traditions. After Atisha, the influence from Indian teachers was limited. Atisha’s main disciple was the layman Dromtönpa, who founded the Kadam-tradition. This tradition does not exist in that form anymore, but it strongly influenced the later schools of Kargyu, Sakya and especially Gelug.
Tibetan teachers like His Holiness the Dalai Lama insist that Tibetan Buddhism these days still carefully reflects the Buddhism as was present in India around the 11th century. He also rejects the term Lamaism, as it suggests as if the Tibetan teachers have developed their own form of Buddhism.
Since from the Buddhism origination in Tibet, it encountered various impress in different period of time and that gave rise to the present Tibetan Buddhism, which distinct from its origin Indian and other Asian counterparts, and Tibetan Bon religion has testified one that influenced the most, arguably the prayer flags and burning incense are passed from Bon. Not only the external influences, also the rising of Buddhist scholars within Tibet has contribute for the development of Buddhism and it gradually evolved into four different sects in different period, which are Nyinmapa founded by Guru Padmasambhava, Kadam founded by Atisha and his Tibetan disciple Dromtonpa, this is later converted into Gelug, Kargyu founded by Marpa Lozawa and Kyungpo Nyaljor, Sakya founded by Khon Konchok Gyalpo and Gelug founded by Je Tsongkhapa.