Ayutthaya Historical Park (Thai: อุทยานประวัติศาสตร์พระนครศรีอยุธยา (Pronunciation)) covers the ruins of the old city of Ayutthaya, Phra Nakhon Si Ayutthaya province, Thailand. The city of Ayutthaya was founded by King Ramathibodi I in 1351, though it is likely to be significantly older, based on evidence showing that the area was already populated during the Mon Dvaravati period. Sources further mention that around 850 AD, the Khmers occupied the area and established a stronghold there, naming it Ayodhya, after one of the holiest Hindu cities in India of the same name. The early history of Ayutthaya is connected to this Khmer settlement. Additionally, Prince Damrong has also attested to the existence of a city named Ayodhya, founded by the Khmers ruling from Lopburi at the point where the three rivers meet. An excavation map shows traces of an ancient baray (water reservoir) close to the southwestern tip of Wat Yai Chai Mongkhon, which could have been built on a former important Khmer temple complex.
The principal basis for the aforementioned claims is the Śri Canāśa Inscription K.949 inscription, which is dated to the reign of Bhagadatta, a ruler of Qiān Zhī Fú who presided over Si Thep in the 850s. This inscription has frequently been cited as evidence for Ayutthaya's early existence. It has been argued, however, that the inscription may have been relocated to Ayutthaya at a considerably later time than that indicated by its original dating, a view supported by the absence of archaeological materials in Ayutthaya that can be securely attributed to the period in question. The earliest extant reference to Ayutthaya is found in the Royal Northern Chronicle, which attributes the foundation of the city to a nobleman from the northern region in the year 944.