However, as is always the case with the hereafter, there were conditions attached. Along with all of the normal expectations about living a just life, the ancient Egyptians believed that the preservation of the body was absolutely essential for passage into the afterlife. Over time this led to the development of one of the most complex and ritualized religious systems in history, one which has left us some of the most beautiful sacred monuments and iconography ever created. But even from the earliest days of predynastic Egypt, mummification was an established part of Egyptian religion.