The ruins of Wat Chaiwatthanaram at Ayutthaya. The city was burned and sacked in 1767 by a Burmese army under the King Hsinbyushin.

Indian influence on Siamese culture was partly the result of direct contact with Indian settlers, but mainly it was brought about indirectly via the Indianized kingdoms of Dvaravati, Srivijaya and Cambodia.[24] E:A Voretzsch believes that Buddhism must have been flowing into Siam from India in the time of the Indian Emperor Ashoka of the Maurya Empire and far on into the first millennium after Christ.[24] Later Thailand was influenced by the south Indian Pallava dynasty and north Indian Gupta Empire.[24]

After the fall of the Khmer Empire in the 13th century, various states thrived there, such as the various Tai, Mon, Khmer and Malay kingdoms, as seen through the numerous archaeological sites and artifacts that are scattered throughout the Siamese landscape. Prior to the 12th century however, the first Thai or Siamese state is traditionally considered to be the Buddhist kingdom of Sukhothai, which was founded in 1238.