building techniques and materials: Africa 143 Cupboard door (wood, carved ivory, and marquetry); Egypt, second half of the 13th century (Los Angeles County Museum of Art, the Madina Collection of Islamic Art, gift of Camilla Chandler Frost, Photograph © 2006 Museum Associates/LACMA) of their ranges by migrating Bantu-speaking peoples whose origins were in West Africa These immigrants built homes made of clay or wattle and daub Wattle and daub is mud dried over intertwined strips of wood The homes were almost universally round, with square structures appearing only after European intrusions The clay houses required occasional rebuilding because of erosion caused by rain In most of the central African Bantuspeaking communities, women were the house builders They quarried the clay themselves, usually from pits near rivers, and transported the clay to their building sites Walls were built in layers about inches high and forming a circle except for an opening for a doorway These layers would be laid one atop another and allowed to dry Roofs varied according to custom and taste Usually the roofs were somewhat flattened cones made of wooden frames overlaid with leaves or rushes The edge of the roof extended beyond the outside of the wall, which kept rainwater away The center was sometimes topped by a finial (a type of building ornament) In West Africa the basic structures had a very ancient history Evidence for ancient population movements is hard to find, but it appears that people who lived in the Sahara grasslands from 5095 to 2780 b.c.e migrated south into much of West Africa, under pressure from the expanding Sahara Desert and raids from well-armed nomads They brought with them an ancient form of house building Their basic structures were made of wattle and daub, with the wattle consisting of wooden posts interlaced with branches or wicker and the daub consisting of mud The roofs were thatched The Fulani in West Africa built their homes in small groups surrounded with barriers made of brush They and other groups, such as the Mandinka, continued to build circular houses throughout the medieval era At the beginning of the period in the city of Jenne-jeno, only round houses were built, but by the 1100s square structures were being erected Inhabitants of Jenne-jeno also developed mud bricks, which were dried in the sun before being used in construction There is evidence that this development occurred throughout the kingdom of Ghana, in particular The floors of buildings were usually smoothed earth As the threat of war grew during the later medieval era, the people of Jenne-jeno built a 12-foot-thick wall 1.2 miles in length around their city It was made of mud It is likely that more such walls will be found as archaeologists study West African cities more closely In eastern and southeastern Africa are found the spectacular stone structures that excite the most interest among outsiders and archaeologists, yet the most common structures in these areas were made of clay or wattle and daub Until the 900s the clay was laid the way houses in central Africa were usually built, in circular layers It is possible