Manning takes Robin Law's study of Oyo as about as full an interpretation as the evidence then allowed, combining political narrative with cross-sectional analysis of the capital, the army and the provinces.

Cavalry does much of the explanatory work. Horses account for Oyo's power and for the empire's shape, since its reach stopped where the ground no longer suited mounted warfare, and the Alafin's dependence on cavalry he did not personally control sharpened the constitutional crisis. Manning follows the sequence from Gaha's seizure of power in 1754 to Abiodun's counterstroke in 1774, which installed provincial chiefs as a third force at the capital and left the underlying conflict unsettled until provincial revolts brought the state down.

He is warier than Law about the slave trade, suspecting smaller export volumes and reading the surge of the 1780s as an answer to rising prices. The book, he concludes, is careful synthesis rather than new argument.