From stone inscriptions and the architectural style, the Phimai Sanctuary was most likely built at the end of the 11th century during the reign of King Suriyaworaman I. The architectural style is that of the Baphuon style that prospered at the time. However, some characteristics are similar to that of Angkor Wat, which became popular at a later period. Some additions were made to the site in the early 18th Buddhist century during the reign of King Chaiworaman VII when Phimai had close relations with the Khmer Empire. The sanctuary was always a religious site of the Mahayana sect of Buddhism because King Suriyaworaman I and King Chaiworaman VII were followers of the sect.