The history of Egypt is divided into dynasties. From about 5000 BC until 3000 BC, Egypt was not a unified nation and that time is known as the Predynastic period. Around 3000 BC, lands along the Nile River were united under one ruler and the Dynastic period began. Our knowledge of Egyptian civilization rests almost entirely on the tombs and their contents since they were built to endure forever. The early Egyptians believed in a life after death. The body must be preserved if the soul is to live on in the beyond. They built great tombs for their Pharaohs (king), who was not only the supreme ruler but a god. After his death, his body was laid right in the centre of the huge mountain of stone, along with many weapons and food. Even his servants were buried to help him on his journey to the other world.