Tradition has three doors to Bon's spread, Tazig 'Olm Lung Ring' as the first. Second, the oral history claims Bon began 17,000 years ago in central Asia where Persia succeeded Bon's widespread growth with Islam. Third, is the Zhang Zhung kingdom which was located in western Tibet. Bon historians hold many Central Asian Buddhist antiquities are Bon.
The scholarly history of Bon is difficult to clearly ascertain because the earliest surviving documents referring to the religion come from the 9th and 10th centuries, well after Buddhists began the suppression of indigenous beliefs and practices. Moreover, historian Per Kværne notes that "Bon" is used to describe three distinct traditions:
However, other scholars do not accept the tradition that separates Bon from Buddhism; Christopher Beckwith calls Bon "one of the two types of Tibetan Buddhism" and writes that "despite continuing popular belief in the existence of a non-Buddhist religion known as Bon during the Tibetan Empire period, there is not a shred of evidence to support the idea... Although different in some respects from the other sects, it was already very definitely a form of Buddhism."