Ancient Egypt By Karleybrothers02 Period: 2575 BCE to 2150 BCE old kingdom great pyramids of Giza and the Sphinx are built Period: 1975 BCE to 1640 BCE Middle kingdom The Pharaoh Mentuhotep II reunites the two parts of Egypt. Period: 1520 BCE to 1075 BCE New kingdom is the time of greatest prosperity for the Ancient Egyptian civilization.