15th-century Italy and names such as Leonardo da Vinci and Mi chelangelo Buonarroti. Five centu ries earlier, however, on the shores of the Mediterranean there had been a cultural flowering that also de serves to be called a rebirth. In the 10th century the Holy Roman Em pire was founded in southern Ger many, the Byzantine empire was at its height and the Fatimid rulers of North Africa extended their control to Cairo. All these political develop ments were accompanied by great cultural revivals. Arts, crafts and architecture rose to new levels of complexity and subtlety. Such de velopments called for new and exot ic materials, many of which were not available on the shores of the Mediterranean. Where were they to come from?

For at least three materials-gold, ivory and rock crystal (transparent quartz)-the answer was Africa. To bring them from there to the Mediter ranean required a vast international trading network that reached from southern Africa to Sicily. One of the key elements of this network, whose existence has only recently been demonstrated, was provided by Swa hili traders. They obtained gold, ivo ry and rock crystal from their inland contacts and carried them north to the Muslim merchants who relayed them to the Mediterranean world. The Swahili, an African people, were converted to Islam by their trading partners. Partly as a result of their conversion, they emerged as a cohe sive social group that anchored the new trade route and helped to lay the groundwork for the lOth-centu ry renaissance in Europe. During that renaissance (which amounted to the beginning of the