While in the desert away from Mecca at age 40, Muhammad received revelation from God through angel Gabriel which was later packaged into the Quran. Upon his return to Mecca, he faced rejection from the merchant community and the authority forcing him to leave for Medina. He managed to raise followers at Medina that formed a great army that would regularly attack travellers to and from Mecca. When Muhammad died, his successors formed the custom of staging raids (jihad) against their enemies. They had conquered the Persian Empire, Egypt, North Africa and Spain after a decade of his death (History World Intenational n.p).