Bhutan’s prehistoric period, of which there is neither ethnic, paleobotanic, geographic, or physiographic record, fell roughly between 500 B.C. and A.D. 500. Fire, earthquake, flood, and internecine warfare unfortunately destroyed whatever records may once have existed. The accidental burning in 1832 of the Dzong (monastery-fortress) in Punakha, at that time one of the capital of Bhutan, and the widespread destruction caused at the same site by an earthquake in 1897 were especially responsible for the destruction of Bhutanese historical documents relating to the period. However, a number of stones tools and megaliths available suggest that Bhutan was populated from a relatively early date, probably around 2000-1500 B.C.
Little is known about the early history of Bhutan. From the available artifacts preserved in a small number of ancient monasteries, we find that Bonism, shamanistic ritual, was followed in Bhutan prior to the advent of Buddhism. The Bon tradition and ritual are still practiced in some parts of Bhutan during the celebration of local festivals.
