Tibetan buddhism was originated from Padmasambhava, however the prehistoric shamanistic practice of tibetans known as Bon also had a strong influence.
My personal favorite form of buddhism,
Dzogchen, is often said to have been more of an "origin teaching" of the timeless variety rather than a further development of buddhism perse. It has much in common with Taoism and other traditions which hark to the ancient ways.
Monastaries which were perched on cliffs and mountainsides in Tibet often engaged in esoteric practices involving flying. Robes were used as a gliding apparatus to aid in this pursuit. In fact many different monasataries and schools specialized in different forms of esoteric practices, and were positioned in environments which would benefit them in such a particular way.
An interesting book on some of the more fantastical nature of these practices is called
Magic and Mystery in Tibet. It was written by a traveling buddhist scholar from England, a woman who also spoke tibetan and was sworn as a monk. Also, it was written in the 1920s and at a time when public perception of Tibet was just beginning to form. It was certainly a different era - in the beginning of the book the author writes an account of meeting with the current Dalai Lama who had just returned from a successful military campaign against the Chinese army. There are further accounts of all manner of things, and it is all documented very well and in the utmost sobriety. In fact, she has the air of a skeptic turned believer by sheer weight of evidence. Unfortunately her reserved nature does cause her to keep theories to herself - and thus excludes communication of a possible deeper understanding of those events she writes about. In any event, its a great book - check it out.
My own personal connection to Tibet and its culture, art, spirituality and mysticism is intense to say the least. I have many other old roots as well, but few as indelible.