The Islamic and Byzantine City

Islam first developed and spread in a region of the world where urban civilizations had originated. Caravan routes crisscrossed the Fertile Crescent and the Arabian peninsula several millennia prior to the birth of Christianity, linking the urban-centered civilizations of Mesopotamia, the Nile Valley, and the Indian subcontinent. Overland routes were supplemented by water transit via the Red Sea and the Persian (Arab) Gulf, with transshipping ports in what is now Yemen. Arabia was then more fertile than it is in the early 2000s, and its products (including frankincense and myrrh) were in much demand.

The lands through which the desert caravans passed were divided into the territories of seminomadic tribes that controlled and protected passage. The islands in the narrow gulfs harbored "pirates" who could block passage, pillage, and even sink sailing dhows. If there was not to be a war of all against all, the neighboring communities, whether urban, transhumant, or nomadic, had to develop rules of trust, hospitality, and fair exchange of goods. And there needed to be centers of safety in which members of diverse tribes and communities could mingle without fear.