The history of Egypt has been long and rich, due to the flow of the Nile river, with its fertile banks and delta. Its rich history also comes from its native inhabitants and outside influence. Much of Egypt's ancient history was a mystery until the secrets of ancient Egyptian hieroglyphs were deciphered with the discovery and help of the Rosetta Stone. The Great Pyramid of Giza is the only one of the Seven Wonders of the Ancient World still standing. The Lighthouse of Alexandria, one of the other Seven Wonders, is gone. The Library of Alexandria was the only one of its kind for centuries.
Human settlement in Egypt dates back to at least 40,000 BC with Aterian tool manufacturing.[citation needed] Ancient Egyptian civilization coalesced around 3150 BC with the political unification of Upper and Lower Egypt under the first pharaoh of the First Dynasty, Narmer. Predominately native Egyptian rule lasted until the conquest by the Achaemenid Empire in the sixth century BC.