Worship of nats predates Buddhism in Burma. With the arrival of Buddhism, however, the nats were merged, syncretistically, with Buddhism. The widespread traditional belief among rural folks that there are forest guardian spirits called "taw saung nat"s () and mountain guardian spirits called "taung saung nat"s () appears to act as a deterrent against environmental destruction up to a point. Indiscriminate felling particularly of large trees is generally eschewed owing to the belief that they are dwellings of tree spirits called "yokkazo" () and that such an act would bring the wrath of the nat upon the perpetrator. The most important nat pilgrimage site in Burma is Mount Popa, an extinct volcano with numerous temples and relic sites atop a mountain 1300 metres tall located near Bagan in central Burma. The annual festival is held on the full moon of the month of "Natdaw" (December) of the Burmese calendar. Taungbyone, north of Mandalay in Madaya Township, is another major site with the festival held each year starting on the eleventh waxing day and including the full moon in the month "Wagaung" (August). Yadanagu at Amarapura, held a week later in honour of Popa Medaw ("Mother of Popa"), who was the mother of the Taungbyone Min Nyinaung ("Brother Lords"), is also a popular nat festival. Nats have human characteristics, wants, and needs. They are flawed, having desires considered derogatory and immoral in mainstream Buddhism. During a "nat pwè", which is a festival during which nats are propitiated, "nat kadaw"s ( "lord-consort", i.e. "medium, shaman") dance and embody the nat's spirit in a trance. Historically, the "nat kadaw" profession was hereditary and passed from mother to daughter. Until the 1980s, few "nat gadaw"s were male. Since the 1980s, persons identified by outsiders as trans women or gay male transvestites have increasingly performed these roles. Music, often accompanied by a hsaing waing ("orchestra"), adds much to the mood of the "nat pwè", and many are entranced. People come from far to take part in the festivities in various nat shrines called "nat kun" or "nat naan", get drunk on palm wine and dance wildly in fits of ecstasy to the wild beat of the Hsaing waing music, possessed by the nats.