In the seventh century, Arab groups—a minor and divided people living on a peninsula dominated by harsh deserts—overthrew the Persian Empire and overran the richest provinces of the Byzantine Empire. In less than two centuries, they created a religious empire stretching from the Atlantic Ocean across the Mediterranean to the steppes of Central Asia and the threshold of India. This region of cultural and occasional political unity is known as the “Dar al-Islam,” or House of Islam. This provides the context for Ibn Khaldun’s theory of cyclic dynastic change based on group feeling.

For many Muslims, including Ibn Khaldun, the Prophet Muhammad’s ability to unite the quarreling Arab tribes and his successors’ (the caliphs’) subsequent conquests over seemingly more powerful foes was a true miracle of God (255). Ibn Khaldun, however, also saw parallels in it to other instances of the rise and fall of dynasties. In the Islamic heartlands of the Middle East, the initial four series of four caliphs gave way to a dynasty—the Umayyad Caliphate—that more closely resembled previous empires and lost that particular religious zeal that had propelled Arab groups to victory. The Umayyads in turn gave way to the frontier warriors of the Abbasid