Houses. Most West African towns and cities were built of mud, including the important Malian trading center of Djenne. Round mud huts with thatched or straw roofs were typical architecture, especially in the kingdoms of Ghana to the west and Songhai to the east. However, houses and the ruler's castle in the Sudanic kingdom of Zaghawa were made of gypsum, and in Ghana some houses, mosques, and schools were built from carved and joined stone. In the mid eleventh century, working from earlier sources, the Spanish Muslim geographer al-Bakri gave a detailed account of the Kingdom of Ghana, describing the houses in the capital, Kumbi Saleh (in present-day southern Mauritania). Built of stone, these houses had two stories, with the lower floor of each serving as a storeroom. They were built close together with narrow alleys between them. The city...