In medieval Egypt, perhaps the most significant event to occur since the unification of the Two Lands by King Menes in ancient times was the Arab conquest. The Arab Conquest of Egypt. The conquest of the country by the armies of Islam under the command of the Muslim hero, Amr ibn al Aas, transformed medieval Egypt from a predominantly Christian country to a Muslim country in which the Arabic language and culture were adopted even by those who clung to their Christian or Jewish faiths.