Buddhism, the great eastern religion founded by the Indian Prince Siddhartha Gautam 600 years before the birth of Christ, first appeared in Thailand during the 3rd century B.C. in the area of the present day provincial capital Nakhom Pathom. Once established, it proved such a durable and pervasive force that some ethnic groups who migrated into that area during the Dvaravati period readily adopted it as their state religion.

As its inception, Buddhism had been a reaction against Brahmanism, eschewing Brahmanism's emphasis on caste and dogma regarding sacrifice and ritual. At the same time, it modified Brahmanic concept of karma and rebirth.

Briefly, Buddhism teaches that one's life does not begin with birth and end with death but is a link in a chain of lives, each conditioned by volitional acts (karma) committed in previous existences. The concept of karma, the law of cause and effect, suggest that selfishness and craving results in suffering. Conversely, compassion and love brings happiness and well-being. Therefore, only by eliminating desire can one find peace of mind. The ideal Buddhist aspiration is to attain perfection through Nivana, an indescribable, immutable state unconditioned by desire, suffering or further rebirth, in which a person simply is, yet is completely at one with his surroundings.

After its introduction to Thailand, Buddhism gained wide acceptance because its emphasis on tolerance and individual initiative complemented the Thais' cherished sense of inner freedom. Fundamentally, Buddhism is an empirical way of life. Free of dogma, it is a flexible moral, ethical, and philosophical framework within which people find room to fashion their own salvation.

Sukhothai's King Ramkhamhamhaeng (1275 - 1317 A.D.) established Theravada Buddhism as Thailand's dominant religion. It reached its height under the reign of King Ramkhamhaeng'sgrandson, King Li Thai (1347 - 1368 A.D.), when about 30 volumes of the Buddhist scriptures were studied and rewritten by the king into one volume, the Tribhumikatha, a treatise on Buddhist cosmology and the three planes of existence-Sensuous, Corporeal, and Incorporeal. Not only was this the first Buddhist treatise by a Thai, but it was also the first known Thai Buddhist and didactic literary work. The Tribhumikatha's impact on religious arts such as mural paintings can be seen today in many monasteries in various provinces.

Through the centuries Buddhism has been the main force in Thai cultural development. Much of classic Thai art, particularly architecture, sculpture, painting and early literature, is really Buddhist art. Currently out of 59 million people in Thailand, about 95 per cent are Buddhist.