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 ("king of the world", or "king of kings") on Phnom Kulen. The empire ended with the fall of Angkor in the 15th century.
The history of Angkor as the central area of settlement of the historical kingdom of Kambujadesa is also the history of the Khmer kingdom 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 civilisation is derived primarily from:
Archaeological excavation, reconstruction and investigation
Stone inscriptions (most important are foundation steles of temples), which report on the political and religious deeds of the kings
Reliefs in a series of temple walls with depictions of military marches, life in the palace, market scenes and also the everyday lives of the population
Reports and chronicles of Chinese diplomats, traders and travellers.