"Myanmar (Burma) is a majorly a Buddhist majority country with a significant minority population residing in the country. (Section 361) of the Constitution states that "The Union recognizes Buddhism as the state religion." According to both the 2016 census of the Burmese government Buddhism is the dominant religion, of 90% of the population, practiced especially by the Bamar, Rakhine, Shan, Mon, Karen people and Chinese ethnic groups. Bamar people also practice the Burmese folk religion under the name of Buddhism. The new constitution provides for the freedom of religion; however, it also grants broad exceptions that allow the regime to restrict these rights at will. Ethnic minorities practice Christianity (6.3%, particularly the Chin, Kachin and Karen people), Islam (2.1%, particularly the Rohingya, Malay, people from Yangon and other minorities), and Hinduism (0.5%, particularly by Burmese Indians).
Nat worship is common in Myanmar. Nats are named spirits and shrines can be seen around the country, either standing alone, or as part of Buddhist temples. Nat worship has a relationship with Myanmar Buddhism and there is a recognised pantheon of 37 nats."
(from Wikipedia)
Buddhism in Myanmar A Short History (by Bischoff)