Ancient Egypt was a civilization of ancient Northeastern Africa, concentrated along the lower reaches of the Nile River in what is now the modern country of Egypt. It is one of six civilizations to arise independently. Egyptian civilization followed prehistoric Egypt and coalesced around 3150 BC (according to conventional Egyptian chronology) with the political unification of Upper and Lower Egypt under the first pharaoh Narmer (commonly referred to as Menes). The history of ancient Egypt occurred in a series of stable Kingdoms, separated by periods of relative instability known as Intermediate Periods: the Old Kingdom of the Early Bronze Age, the Middle Kingdom of the Middle Bronze Age and the New Kingdom of the Late Bronze Age.