In the 5th century, the Middle East was separated by empires and their spheres of influence; the two most prominent were the Persian Sasanian Empire, centered in what is now Iran, and the Byzantine Empire in Anatolia (modern-day Turkey). The Byzantines and Sasanians fought with each other continually, a reflection of the rivalry between the Roman Empire and the Persian Empire seen during the previous five hundred years. The fighting weakened both states, leaving the stage open to a new power. Meanwhile, the nomadic Bedouin tribes who dominated the Arabian desert saw a period of tribal stability, greater trade networking and a familiarity with Abrahamic religions or monotheism.