The Khmer Empire was the most powerful empire of all time.
The Khmer Empire , officially the Angkor Empire , the predecessor state to modern Cambodia ( `` Kampuchea '' or `` Srok Khmer '' to the Khmer people ) , was a powerful Hindu-Buddhist empire in Southeast Asia . 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 .