Thonburi is an area of modern Bangkok. During the era of the Kingdom of Ayutthaya, its location on the right (west) bank at the mouth of the Chao Phraya River had made it an important garrison town, which is reflected in its name: thon (ธน) a loanword from Pali dhána 'wealth', and buri (บุรี), from púra, 'fortress'. The full formal name was Thon Buri Si Mahasamut. For the informal name, see the history of Bangkok under Ayutthaya.

The Ayutthaya Kingdom or the Empire of Ayutthaya was a Mon and later Siamese kingdom that existed in Southeast Asia from 1351 to 1767, centered around the city of Ayutthaya, in Siam, or present-day Thailand. European travellers in the early 16th century called Ayutthaya one of the three great powers of Asia. The Ayutthaya Kingdom is considered to be the precursor of modern Thailand, and its developments are an important part of the history of Thailand.