Access to the Sea. In the area of water transport, the medieval Islamic world presents a double face. The Mediterranean Sea and the Indian Ocean formed water frontiers to which Muslims reacted quite differently. The empire conquered by the Arabs between 632 and 711 incorporated an enormous extent of coastline: the Mediterranean coast of Iberia (Spain), the Atlantic coast of Morocco, the southern and eastern coasts of the Mediterranean Sea, all the east and half of the west coast of the Red Sea, the southern coast of the Caspian Sea, and the entire Indian Ocean coast from Yemen to the mouth of the Indus including the Persian Gulf. No empire had comparable access to the sea until the Portuguese and Spanish explorations of the fifteenth century. These coastlines do not all have the same importance, however, in political and economic calculations. Geographically...