What Was the Trans-Saharan Trade? Gold, Salt and a Sea of Sand

The Sahara was crossed occasionally before, by horse and ox cart along routes recorded in rock art, and regular commercial traffic became possible only with the dromedary camel, introduced to North Africa from Arabia around the first to third centuries AD and in widespread use by the fourth. A camel can carry around two hundred kilograms, travel roughly forty kilometres a day, go ten days or more without water, and regain condition on thorny vegetation that would starve any other pack animal. Caravans could reach a thousand animals and occasionally many more, and the crossing took two to three months between the fringes of cultivation on each side. Navigation depended on knowing the wells, since the route was defined by water rather than by terrain, and a guide who missed one killed the caravan, which is why Berber and later Tuareg specialists controlled the desert legs and were paid accordingly.

The exchange looks strange until the geography is understood. West Africa's savanna and forest zones held enormous alluvial gold deposits, particularly in Bambuk, Bure and later the Akan region, and almost no salt, because the climate is too wet for evaporation deposits and the body loses salt rapidly in heat. The central Sahara had the reverse: vast salt deposits at places such as Taghaza and Taoudenni, where the mines were worked in appalling conditions and the buildings were reportedly constructed from salt blocks because no other material was available, and no gold at all. Each side traded what was abundant for what was necessary, which is why accounts describe salt exchanging for gold at rates approaching weight for weight at certain times and places. The other goods moved alongside:

• •North to south: salt, copper, horses, textiles, glass beads, manufactured goods, paper and books
• •South to north: gold, ivory, kola nuts, leather, ostrich feathers, gum arabic and pepper
• •Enslaved people in large numbers, taken north across the desert over centuries in a trade whose total is estimated in the millions and which is far less discussed than the Atlantic trade
• •Ideas, law, literacy in Arabic, and Islam itself, which spread along the routes with merchants rather than by conquest in most of West Africa

Control of the southern end of the routes produced a succession of large states. Ghana, unrelated to the modern country and centred further north, dominated from perhaps the eighth century by taxing the trade rather than by mining the gold, whose sources its rulers kept secret. Mali succeeded it in the thirteenth century under Sundiata and reached its height under Mansa Musa, whose pilgrimage to Mecca in 1324 crossed Egypt with a retinue of thousands and enough gold to depress the Cairo gold price for years, an episode that put a West African king on a European map, the Catalan Atlas of 1375, holding a nugget. Songhai followed, based at Gao, and became the largest of the three before being destroyed by a Moroccan army with firearms at Tondibi in 1591. Each state's wealth came from taxing goods in transit and from controlling the trading cities, and each maintained an administration, a standing army and a legal system funded by that revenue.

The cities at the desert's southern edge, above all Timbuktu, Djenne and Gao, became something more than markets. Timbuktu, at the point where the Niger bends closest to the desert, transferred goods between camel and river transport, and by the fifteenth and sixteenth centuries it held a scholarly community, several centres of learning including the Sankore mosque, and a manuscript culture of considerable size. Leo Africanus, visiting around 1510, reported that books brought from the north sold for more than any other merchandise. The manuscripts, on astronomy, mathematics, medicine, law, theology, poetry and correspondence, numbered in the hundreds of thousands across private family libraries, and their survival became an urgent matter in 2012 when armed groups occupied the city and librarians and residents smuggled a large proportion of them out to Bamako in boats and on donkeys. The episode corrected, for a wide audience, the persistent assumption that precolonial West Africa had no written scholarly tradition.

The decline was caused mainly by a change elsewhere. Portuguese ships reached the West African coast from the 1440s and began buying gold directly at the Gulf of Guinea, which meant that goods no longer had to cross the desert to reach a European buyer, and the sea route was cheaper and faster. The Atlantic slave trade then reoriented West African economies towards the coast entirely. The Moroccan conquest of Songhai in 1591 destroyed the political order that had protected the southern routes without replacing it. The trade did not stop, and salt caravans continued into the twentieth century and survive today on a small scale, with the azalai from Timbuktu to Taoudenni still run, though most salt now travels by lorry. What remains is the cultural geography the trade created: the Islamic scholarly tradition of the Sahel, the trading diasporas that still link the region, the architecture of mud-brick mosques, and the fact that the wealthiest individual in recorded history, by several estimates, was a fourteenth-century West African king whose fortune came from taxing camels.

The camel, adopted in North Africa by the fourth century, made regular desert crossings possible, and the trade exchanged Saharan salt for West African gold because each region lacked what the other had in abundance. It funded the successive empires of Ghana, Mali and Songhai, which taxed goods in transit, and made Timbuktu a centre of Islamic scholarship with hundreds of thousands of manuscripts. Enslaved people were carried north in large numbers over centuries, and the trade declined once Portuguese ships reached the West African coast and bought gold directly.