■ Trade: this was one of the main sources of wealth. In the cities, there were markets (souks) where all types of product were sold. For commercial exchange, they used coins (dinar, dirham, fals). The Muslims developed external trading both over land and by sea via different routes, such as the Silk Road. Silk, precious stones and spices were brought to the Muslim cities from the East, gold and ivory arrived from Africa, etc.