The Ayutthaya Kingdom or the Empire of Ayutthaya was a Thai 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 (alongside Vijayanagara and Ming China), although the Chinese chronicles recognise the kingdom as one of its tributary states. The Ayutthaya Kingdom is considered to be the precursor of modern Thailand, and its developments are an important part of the history of Thailand.
The name Ayutthaya originates from Ayodhya, a Sanskrit word. This connection stems from the Ramakien, Thailand's national epic.