The Khmer Empire (802–1431), officially the Angkor Empire, in the modern Cambodia, was a Hindu-Buddhist empire in Southeast Asia.

Its greatest legacy is Angkor, in present-day Cambodia, which was the site of the capital city during the empire's zenith. The majestic monuments of Angkor, such as Angkor Wat and Bayon, bear testimony to the Khmer Empire's immense power and wealth, impressive art and culture, architectural technique, aesthetics achievements, and the variety of belief systems that it patronized over time. Satellite imaging has revealed that Angkor, during its peak in the 11th to 13th centuries, was the largest pre-industrial urban center in the world.

Edited from:https://en.wikipedia.org/wiki/Khmer_Empire