When did Shinto first develop?

Shinto cannot be traced to its beginnings, because until the 5th cent. (when Chinese writing was introduced into Japan) the myths and rituals were transmitted orally. The written record of the ancient beliefs and customs first appeared in the Kojiki[records of ancient matters], prepared under imperial order and completed in A.D. 712. From those first Japanese accounts of the religion of times then already far past, it can be seen that a worship of the forces and forms of nature had grown into a certain stage of polytheism in which spiritual conceptions had only a small place. Nor was there any clear realization of a personal character in the beings held to be divine, and there were practically no images of the deities.