From the 6th century the Funan kingdom's importance as a port of call declined, and Cambodia's population gradually concentrated along the Mekong and Tonlé Sap Rivers, where the majority remains today. The move may have been related to the development of wet-rice agriculture. From the 6th to 8th centuries it was likely that Cambodia was a collection of competing kingdoms, ruled by autocratic kings who legitimised their absolute rule through hierarchical caste concepts borrowed from India.

This era is generally referred to as the Chenla period. Again, like Funan, it is a Chinese term and there is little to support the idea that the Chenla was a unified kingdom that held sway over all of Cambodia. In­deed, the Chinese themselves referred to 'water Chenla' and 'land Chenla'. Water Chenla was located around Angkor Borei and the temple mount of Phnom Da, near the present-day provincial capital of Takeo; and land Chenla in the upper reaches of the Mekong River and east of the Tonle Sap lake, around Sambor Prei Kuk, an essential stop on a chronological jaunt through Cambodia's history.

The people of Cambodia were well known to the Chinese, and gradu­ally the region was becoming more cohesive. Before long the fractured kingdoms of Cambodia would merge to become the greatest empire in Southeast Asia.