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 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. The Ayutthaya Kingdom emerged from the mandala or merger of three maritime city-states on the Lower Chao Phraya Valley in the late 13th and 14th centuries (Lopburi, Suphanburi, and Ayutthaya). The early kingdom was a maritime confederation, oriented to post-Srivijaya Maritime Southeast Asia, conducting raids and tribute from these maritime states. After two centuries of political organization from the Northern Cities and a transition to a hinterland state, Ayutthaya centralized and became one of the great powers of Asia. From 1569 to 1584, Ayutthaya was a vassal state of Toungoo Burma; but quickly regained independence. In the seventeenth and eighteenth centuries, Ayutthaya emerged as an entrepôt of international trade and its cultures flourished. The reign of Narai (r. 1657–1688) was known for Persian and later, European, influence and the sending of the 1686 Siamese embassy to the French court of King Louis XIV. The Late Ayutthaya Period saw the departure of the French and English but growing prominence of the Chinese. The period was described as a "golden age" of Siamese culture and saw the rise in Chinese trade and the introduction of capitalism into Siam, a development that would continue to expand in the centuries following the fall of Ayutthaya.
Ayutthaya's failure to create a peaceful order of succession and the introduction of capitalism undermined the traditional organization of its elite and the old bonds of labor control which formed the military and government organization of the kingdom. In the mid-18th century, the Burmese Konbaung dynasty invaded Ayutthaya in 1759–1760 and 1765–1767. In April 1767, after a 14-month siege, the city of Ayutthaya fell to besieging Burmese forces and was completely destroyed, thereby ending the 417-year-old Ayutthaya Kingdom. Siam, however, quickly recovered from the collapse and the seat of Siamese authority was moved to Thonburi-Bangkok within the next 15 years.
In foreign accounts, Ayutthaya was called "Siam", but people of Ayutthaya called themselves Tai, and their kingdom Krung Tai (Thai: กรุงไท) meaning 'Tai country' (กรุงไท). It was also referred to as Iudea in a painting requested by the Dutch East India Company. The capital city of Ayutthaya is officially known as Krung Thep Dvaravati Si Ayutthaya (Thai: กรุงเทพทวารวดีศรีอยุธยา), as documented in historical sources.