Khmer Empire relied on the establishment of secure food supplies and in the khmer Empire, fish and rish were their main food resources. Rice production was very important in the expansion and maintenance of the khmer empire. The Khmer Empire created a hydraluic supply to control the water supply from rainfall to their crops as well as the retreat method. They constructed dams, reservoirs and irrigation canals around the Tonle Sap to collect water during the wet season, when there was a lot of rain. In the dry season, the shortage of a good water supply made it very difficult to grow big quantities of rice.