Thailand is a large country in southeast Asia where approximately 95% of the population call themselves Buddhist. Animism and Brahmanism were the main religions until Theravada Buddhism became the official religion during the reign of King Rama Khamheng (1275-1317). This happened in the 12th century, due in part to missionary monks from Sri Lanka.
As it is actually practiced by the majority of the people, Thai Buddhism is more animistic and Brahmanical magic and divination than it is the teachings of the Buddha. Efforts by reformers like Buddhadasa to return to more authentic Buddhism have met with little success beyond the educated class. Thailand’s king is one of only two Buddhist monarchs left in the world.
Sangha, State and Society - Thai Buddhism in History, Ishii Yoneo, 1986.