Information about activity of the Atlanteans in Tibet and what they left for their descendants, we can find in books of Lobsang Rampa
What happened to Atlantean culture in Tibet after that — this we do not know. What we do know is that Tian tribes invaded Tibet…
By the beginning of second millennium the religion of Tibetans (Bon) did not prevent them from launching predatory campaigns against their neighbors, killing one another in the struggle for power, sacrificing animals (including horses, to which they would break their legs first) to “malicious gods”
Buddhism came to Tibet from India in the VII — VIII centuries A.D. and gradually, though not without difficulties, started to prevail  in this region. What can be said about its Tibetan form that exists today?
On one hand, Tibetan spiritual adepts of this tradition developed very efficient systems of consciousness training that lead to the highest spiritual achievements
On the other hand — the principle of Love-compassion, which the Founder of Buddhism — Gautama Buddha — made the essence of His Teaching, was abandoned. Namely, killing of animals was permitted. Moreover, black magic was “legitimized” in the form of seeking cooperation from non-incarnate hellish beings that started to be named “wrathful deities”
A reasonable person understands that “whomever one is friends with, from them one learns”. Wise people seek the association with the Primordial Consciousness.
But foolish ones… What happens to them I described in the book , where I gave an example of followers of this perverted tendency in Saint Petersburg.
Those who were supposed to explain all this to the believers were Dalai Lamas. But…
Moreover, it is in Tibet where the concept originated that the Perfection can be attained not by means of cognizing the Primordial Consciousness and Mergence with It, but as a result of “momentary enlightenment”. It was believed that for the sake of attainment of this “momentary enlightenment” disciples had to be insulted, humiliated, and beaten, preferably when they do not expect it.
The following story was included in the “heroic epos” of Tibetan Buddhism. A master with his disciple who were starving finally approached a village. The master sent the disciple to ask the villagers for some food. The latter came back with the food that he had been given, hoping to also satisfy his hunger. But the master devoured all the food himself… and told the disciple to drink a stinking slush from the runoff ditch… And then beat him with his dirty shoe on his face… The disciple, as the story goes further, as a result attained a “momentary enlightenment”…
(This tendency of obtruding this kind of “enlightenment” on other people became popular among many pseudo-Buddhists with devilish souls, especially those of some extremely perverted “Buddhist schools” in China and in other countries, including Russia).
To make it easier for a not too competent reader to understand what it is all about I will clarify that the term “Enlightenment” implies transformation of the individual consciousness of an embodied man into Light, when it gets close to the state of the Creator. (remember, “God is Light…”? (1 John, 1:5)). This Light-Love then starts shining out of the body, being radiated by the consciousness that abides in it. A man acquires such a state, which we have already discussed, as a result of the refinement of consciousness and growing it in the subtlest eons. I must emphasize: this can be achieved only through the growth of consciousness as refined and tender Love-Peace, followed by Mergence of it with the Fiery Manifestation of the Creator (or “Clear Light”, in Buddhist terms). True Enlightenment can be attained only as a result of realization of the functions of the spiritual heart. And not by means of cultivating aggressive arrogance, rudeness, and ability to suppress other people with the power of devilish-quality consciousness.
But modern proponents of Tibetan Buddhism instead of development of the spiritual heart and refinement of consciousness teach their followers… to plug lower foramens of the body with corks — so that they will not fall down to hell out of them…
…Thus, in Tibet we can observe the same typical situation of gradual degradation — following the stages of development and culmination — of the great and pure Teaching, which is being displaced by human ignorance.
…And Chinese Cultural Revolution swept Tibet away.