The Middle Kingdom of Egypt or The Period of Reunification was the period in Ancient Egyptian history from 2050 BC and 1800 BC from reunification of Egypt and the impulse of Mentuhotep II of the Eleventh dynasty towards the end of the Twelfth dynasty. ome scholars also include the Thirteenth Dynasty of Egypt wholly into this period as well, in which case the Middle Kingdom would finish c. 1650, while others only include it until Merneferre Ay c. 1700 BC, last king of this dynasty to be attested in both Upper and Lower Egypt. During the Middle Kingdom period, Osiris became the most important deity in popular religion.