Revealed Law. At first, political and legal organization in Islam was simple. From the time he began preaching publicly, about 612, the Prophet Muhammad guided a small community of followers at Makkah, all of whom were connected with the local tribe known as the Quraysh. Because they knew each other personally, no institutionalized organization was needed. However, when visitors from the oasis of Yathrib, 450 kilometers to the north, decided to become Muslims in 620, they took an oath of allegiance to the Prophet and renewed it the following year. In 622, when the Prophet and a few dozen of his Makkan companions, called the Muhajirun (Emigrants), settled Yathrib, which was then renamed Madinah (the community governed by divine law), they were joined by large numbers of people from that oasis, called the Ansar (Helpers), and the community required more political organization. The earliest expression of this institutionalization of government is found...