Final answer:
Salt was extremely valuable in medieval sub-Saharan Africa for its preservative properties, leading it to be traded across the Sahara alongside gold.
Step-by-step explanation:
Historically, trans-Saharan traders moved salt across the desert into sub-Saharan Africa because it was a highly valued resource, almost as precious as gold. Salt's preservative qualities made it essential for food storage. The demand for gold and salt drove the establishment of trade routes, with cities such as Timbuktu, Gao, and Djenné emerging as key centers of commerce. Over time, as gold deposits were found further east, important trade routes indeed shifted to accommodate these new sources.
The significance of salt, alongside gold, in the medieval African empires cannot be overstated. Salt was mined from places like Taghaza and was so valuable that it was stored in treasuries alongside gold. The quest for gold led to explorations and trade that connected West Africa with the Mediterranean, Europe, and beyond. Moreover, the expansion of gold production and new trade routes into the goldfields of the Akan forest in present-day Ghana played a pivotal role in shaping the trade dynamics of the region.