Any world religion will mix with the society it encounters. For example, there is a very distinct form of Catholicism in Central America that is very different (though they share core principles) from Catholicism in Italy or the Philippines. read more
Tibetan Buddhism borrows from the cultural sphere that was in place before Buddhism entered the region and mixes the core values of Buddhism with the local culture. The local tradition was itself a blend of a multitude of traditions and some tie elements of Iranian (Zoroastrianism) culture as well as a blend of the indigenous Shamanism in the region. Check out the following articles below for more information on the relationship between Bon and Tibetan Buddhism. read more
Tibetan Buddhism, though based on Indian Buddhist thought, also has roots in Bon, the Shamanistic religion of Tibet. In fact there is a documentary about Tibetan oracles, that features both the Dalai Lama and his younger brother, I believe it was Tenzin Choegyal. read more