After securing his authority over the entire Achaemenid Empire, Darius I, also called Darius the Great, embarked on a campaign to Egypt where he defeated the armies of the Pharaoh and secured the lands that Cambyses had conquered while incorporating a large portion of Egypt into the Achaemenid Empire.Through another series of campaigns, Darius I would eventually reign over the territorial apex of the empire, when it stretched from parts of the Balkans (Thrace-Macedonia, Bulgaria-Paeonia) in the west, to the Indus Valley in the east.