The area known today as Thailand is believed to have been inhabited for around 4,000 years with relics and other evidence dating back to the Early Bronze Age. The agricultural practice of wet rice production was believed to have been developed in the region and spread through south-east Asia. The Khmer Empire took control and ruled until the 13th century. Subsequently, the Buddhist kingdom of Sukhothai, founded in 1238 and regarded as the first kingdom of Siam, united the region. The Kingdom of Ayutthaya came to power in the 14th century. Thailand continued its trading tradition with its neighbouring states, and with China, India, Persia and Arab lands. Ayutthaya became a trade hub during this era and was a later focus for European traders from England, Netherlands, France and Portugal.

Despite many pressures, Thailand managed to avoid being conquered by the expansionist Europeans, who were dividing up the Asian and Pacific regions, through careful diplomacy.