Claim: The Khmer Empire was a powerful empire.

The Khmer Empire , officially the Angkor Empire , the predecessor state to modern Cambodia -LRB- `` Kampuchea '' or `` Srok Khmer '' to the Khmer people -RRB- , was a powerful Hindu-Buddhist empire in Southeast Asia . The empire , which grew out of the former kingdoms of Funan and Chenla , at times ruled over and/or vassalised most of mainland 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 and aesthetics achievements , as well as the variety of belief systems that it patronised over time . Satellite imaging has revealed that Angkor , during its peak in the 11th to 13th centuries , was the largest pre-industrial urban centre in the world .   The beginning of the era of the Khmer Empire is conventionally dated to 802 CE . In this year , King Jayavarman II had himself declared chakravartin -LRB- `` king of the world '' , or `` king of kings '' -RRB- on Phnom Kulen . The empire ended with the fall of Angkor in the 15th century .