While the Ottoman and Safavid empires brought both a new political unity and a sharp division to the heartland of Islam, two other states performed a similar role on the expanding African and Asian frontiers of the faith. In the West African savannas, the Songhay Empire rose in the second half of the fifteenth century. It was the most recent and the largest in a series of impressive states that operated at a crucial intersection of the trans-Saharan trade routes and that derived much of their revenue from taxing that commerce. Islam was a growing faith in Songhay but was limited largely to urban elites. This cultural divide within Songhay largely accounts for the religious behavior of its fifteenth-century monarch Sonni Ali (r. 1464?–1492), who gave alms and fasted during Ramadan in proper Islamic style but also enjoyed a reputation as a magician and possessed a charm thought to render his soldiers invisible to their enemies. Nonetheless, Songhay had become a major center of Islamic learning and commerce by the early sixteenth century. A North African traveler known as Leo Africanus remarked on the city of Timbuktu:

Slavery too was different in North America than in the sugar colonies. By 1750 or so, enslaved people in what became the United States proved able to reproduce themselves, and by the time of the Civil War almost all enslaved North Americans had been born in the New World. That was never the case in Latin America, where large-scale importation of new enslaved people continued well into the nineteenth century. Nonetheless, many more enslaved people were voluntarily set free by their owners in Brazil than in North America, and free blacks and biracial or multiracial people in Brazil had more economic opportunities than did their counterparts in the United States. At least a few among them found positions as political leaders, scholars, musicians, writers, and artists. Some were even hired as slave catchers.