An economy built on salt
The Taoudeni Basin is a vast sedimentary formation in the Sahara Desert, the remnant of a prehistoric salt lake. For over a millennium, this desolate region was the center of a continental economy powered by one mineral: rock salt. West African empires like the Ghana, Mali, and Songhai controlled immense goldfields to the south but had almost no local sources of salt, a mineral important for human and animal life, especially in hot climates. This geographical imbalance created one of history's most focused examples of supply and demand.
Control of the northern salt mines at places like Taghaza, and later Taoudénit, meant control over the wealth of empires. Rock salt was mined from shallow pits, often dug 5 to 10 meters deep, where the mineral forms in large, stratified slabs. Miners, using basic hand tools, cut these slabs into standardized bars. While tales of salt being traded pound-for-pound with gold might be an exaggeration, the exchange rate was still exceptionally high, making the control of salt production and trade routes a primary geopolitical objective. The empires to the south taxed the salt caravans heavily, generating immense revenue. The earlier mining center, Taghaza, was so completely defined by its product that the 14th-century traveler Ibn Battuta noted its buildings were constructed from salt blocks, with roofs of camel skin.