Prasat Thong was the first king of the Prasat Thong dynasty, the fourth dynasty of the Siamese Ayutthaya Kingdom. Before being king, he defeated a rebellion led by the king's son Phra Sisin by working with Japanese mercenary Yamada Nagamasa. He gained power in 1629 by attacking the palace and placed a puppet king who he would later execute. Under his reign, he subjugated Cambodia but lost Siam's Northern principalities.

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.