For a long time, Western historians downplayed the influence that West Africa’s precolonial political traditions have had on the region’s modern culture, economics, and politics. Even today, scholars’ understanding of the great West African medieval states remains hampered by weak and sometimes contradictory evidence, essentially limited to a small number of Arab sources, some complementary Portuguese and Spanish material, and what’s left of an important oral tradition. The earliest and most powerful of the kingdoms that emerged in West Africa, based on trading networks along the Niger and Senegal Rivers, were the Ghana, Mali, and Songhai empires, which dominated the region in succession from the eighth century to the sixteenth century. Gomez’s ambitious new study uses the available evidence to construct a remarkably detailed understanding of the rise and fall of these empires. His book is particularly cogent on the cultural, political, and administrative lineages that linked them; the growth of Islam; and the institution of slavery. There are more readable introductions to the region’s history, but none that is better informed.