This route across the Sahara Desert was something of an extension of the Silk Road. Beginning in the eighth century, Berber merchants in northern Africa began using camels from the Arabian Peninsula to make regular crossings of the Sahara Desert. Carrying goods acquired from the broader Islamic trading world, they exchanged exotic materials for metal goods, gold, and slaves from such sub-Saharan states as Mali. Like the Silk Road, Europeans sought to break into this trade, which drove much of Atlantic exploration during the fifteenth and...