The Khmer were greatly influenced by India, especially in regards to religion. As a result of Indian immigration to Cambodia, Hinduism became a dominant religion. Hinduism is polytheistic, meaning a belief in many gods, as opposed to just one as in monotheistic religions. One of the central beliefs of Hinduism is reincarnation.
Reincarnation means that one has had and can have more than one life.
Central to reincarnation is the notion of Karma, which determines the status of ones next life based on ones actions in this life. Actions are crucial to a good or bad life. The actions of one during life affects the social position to which one will return. If one is particularly good or reaches a point of enlightenment, one will not return to the material earthly world in the next life. Rather, one will be with the gods in a state of bliss, or nirvana.