Thai Buddha, crafted in lava stone.

Archaeological findings suggest that Buddhism in Myanmar may have been transmitted to Thailand around the 6th century AD. It is possible that Buddhism was already present in Thailand earlier, possibly as early as the year 228 BCE, introduced by Uttar Sthavira, one of the sons of the Indian king Ashoka, an Indian ruler from the 3rd century BCE and a great promoter and protector of Buddhism. The movement that was most prevalent in Thailand between the 8th and 13th centuries was Hinayana Buddhism. Afterwards, Theravada Buddhism spread due to the actions of the then kings of Thailand. This influence mainly came from the contacts that existed at that time with Ceylonese Buddhists. In 1851, Rama IV succeeded his deceased brother Rama III. Rama IV was a Buddhist monk when he ascended the throne, and during his reign, he reformed Buddhism in the country to the form that is still practiced in the early 21st century. He did this by promoting the Dhammayut school, which places great importance on the rules from the Vinaya. He was succeeded by Rama V, who was also an active advocate of Buddhism. He had a Pali Canon published, which is considered one of the most important and complete of its kind by the early 21st century. A later reform ensured that the king took control over the entire sangha in Thailand.