The Khmer Empire was one of the most powerful empires in Southeast Asia. The empire, which grew out of the former kingdom of Chenla, at times ruled over and/or vassalized parts of modern-day Laos, Thailand, Vietnam, Burma, and Malaysia. Its greatest legacy is Angkor, in present-day Cambodia, which was the site of the capital city during the empire's zenith. Angkor bears testimony to the Khmer empire's immense power and wealth, as well as the variety of belief systems that it patronised over time. The empire's official religions included Hinduism and Mahayana Buddhism, until Theravada Buddhism prevailed, even among the lower classes, after its introduction from Sri Lanka in the 13th century. Modern researches by satellites have revealed Angkor to be the largest pre-industrial urban center in the world.
The history of Angkor as the central area of settlement of the historical kingdom of Kambujadesa is also the history of the Khmer from the 9th to the 13th centuries.
From Kambuja itself — and so also from the Angkor region — no written records have survived other than stone inscriptions. Therefore the current knowledge of the historical Khmer civilization is derived primarily from: