The history of Egypt is the longest continuous history, as a unifie state, of any country in the world. The Nile valley forms a natural geographic and economic unit, bounded to the east and west by deserts, to the north by the sea and to the south by the Cataracts of the Nile. The need to have a single authority to manage the waters of the Nile led to the creation of the world's first state in Egypt in about 3000 BC. Egypt's peculiar geography made it a difficult country to attack, which is why Pharaonic Egypt was for so long an independent and self-contained state. The Hyksos were among the earliest foreign rulers of Egypt, but the ancient Egyptians regained control of their country after the Hykso period. The Neo-Assyrian Empire also controlled Egypt for a while before native Egyptians regained control.