The material revealed at Mecca and the material revealed at Medina differ, and the difference is one of the standard tools of Quranic study. The Meccan passages are largely concerned with the oneness of God, the resurrection and judgment, the fate of earlier peoples who rejected their prophets, and the moral demands on the individual. The Medinan passages address a community that has to govern itself: inheritance, marriage and divorce, debt, warfare, treaties, the treatment of other religious groups within the city.
Several of the practices that define Muslim life are established in this period. The direction of prayer was changed from Jerusalem to Mecca. The fast of Ramadan was prescribed. The alms tax became an institution rather than a virtue. The document usually called the Constitution of Medina set out the terms on which the emigrants, the local Muslims and the Jewish tribes of the city belonged to a single community for purposes of defence while keeping their own religion and law.
For the historian this is where Islam becomes visible as a social order rather than a message, and for Islamic law it is the period that supplies most of the precedents. The consequence is a religion in which the founder was also a legislator, a judge and a head of state, which distinguishes the shape of Islamic tradition from that of the traditions it grew up beside.