Tutankhamun, or Tutankhamen, was an Egyptian pharaoh who ruled c. 1332 – 1323 BC during the late Eighteenth Dynasty of ancient Egypt. Born Tutankhaten, he instituted the restoration of the traditional polytheistic form of ancient Egyptian religion, undoing a previous shift to the religion known as Atenism. Tutankhamun's reign is considered one of the greatest restoration periods in ancient Egyptian history.