Defensive Fortifications. Fortresses, walls, ramparts, and guarded gates were built as defensive shields against invaders. The cities of Kebbi, Kano, and Djenne were fortified by walls. When invaders could not gain access to such protected cities, they often laid siege to them. The city of Djenne is said to have been held under siege by the Songhai forces of Sunni Ali (ruled 1464-1492) for more than seven years. During that long period Ali's soldiers cultivated crops outside the walled city. In the sixteenth century the seven layers of stone walls around Kebbi ensured the successful defense of the city against mighty Songhai forces.

Military Technology. Archeological findings have revealed that iron smelting and ironworking in West Africa date back as early as 500 B.C.E. By that time the people of Nok had mastered ironwork technology. Early West African weaponry...