The six centuries of the Khmer Empire are characterised by unparalleled technical and artistic progress and achievements, political integrity and administrative stability. The empire represents the cultural and technical apogee of the Cambodian and Southeast Asian pre-industrial civilisation.^[19] The Khmer Empire was preceded by Chenla, a polity with shifting centres of power, which was split into Land Chenla and Water Chenla in the early 8th century.^[20] By the late 8th century Water Chenla was absorbed by the Malays of the Srivijaya Empire and the Javanese of the Shailandra Empire and eventually incorporated into Java and Srivijaya.^[21]

Jayavarman II, is widely regarded as the king who set the foundations of the Angkor period. Historians generally agree that this period of Cambodian history began in 802, when Jayavarman II conducted a grandiose consecration ritual on the sacred Mount Mahendraparvata, now known as Phnom Kulen.^[22] In the following years, he extended his territory and established a new capital, Hariharalaya, near the modern-day town of Roluos.^[23] He thereby laid the foundation of Angkor, which was to arise some 15 kilometres (9.3 mi) to the northwest. The successors of Jayavarman II kept extending the territory of Kambuja. Indravarman I (reigned 877–889) managed to expand the kingdom without wars and initiated extensive building projects, which were enabled by the wealth gained through trade and agriculture. Foremost were the temple of Preah Ko and irrigation works. The water management network depended on elaborate configurations of channels, ponds, and embankments built from huge quantities of clayey sand, the available bulk material on the Angkor plain. Indravarman I developed Hariharalaya further by constructing Bakong circa 881. Bakong in particular bears striking similarities to the Borobudur temple in Java, which suggests that it may have served as the prototype for Bakong. There may have been exchanges of travellers and missions between Kambuja and the Sailendras in Java, which would have brought to Cambodia not only ideas, but also technical and architectural details.^[24]