The Old Kingdom is the name given to the period in the 3rd millennium BC when Egypt attained its first continuous peak of civilization – the first of three so-called "Kingdom" periods, which mark the high points of civilization in the lower Nile Valley (the others being Middle Kingdom and the New Kingdom). The term itself was coined by eighteenth-century historians and the distinction between the Old Kingdom and the Early Dynastic Period is not one which would have been recognized by Ancient Egyptians. Not only was the last king of the Early Dynastic Period related to the first two kings of the Old Kingdom, but the 'capital', the royal residence, remained at Ineb-Hedg, the Ancient Egyptian name for Memphis. The basic justification for a separation between the two periods is the revolutionary change in architecture accompanied by the effects on Egyptian society and economy of large-scale building projects.