The name Thailand was invented in 1939. The country it described, formerly called Siam, had been defined by borders drawn in the 1890s and 1900s. Its capital, Bangkok, had been founded in 1782 in succession to an older city, Ayutthaya, destroyed 15 years earlier. Ayutthaya had been one of the great port cities of Asia, with trading links stretching from Persia to China, and a political and economic hinterland focused on the basin of the Chao Phraya river system.

The society of this hinterland had evolved over prior centuries in a pattern that was similar throughout Southeast Asia. The landscape was dominated by tropical and subtropical forest. People clustered in city-states. Society was organized around personal ties of service and protection. An era of warfare from the 13th to 16th centuries saw the emergence of a powerful militaristic kingship buttressed by Brahmanical ritual, trading profits, and systems for marshalling forced labour. But since the 17th century, this social and political order had begun to shift with the expansion of a commercial economy, a loosening of labour ties, the emergence of an aristocracy, and the new vitality of Theravada Buddhism.