Final answer:
The Mali Empire mainly exchanged gold dust for salt, a vital commodity for food preservation and health. Salt, alongside gold, significantly contributed to the empire's wealth through trade taxes.
Step-by-step explanation:
The Mali Empire, renowned for its wealth and trade in the medieval period, conducted extensive trade with surrounding regions. One of the main trades of the Mali empire involved exchanging gold dust for another invaluable commodity that was essential for preserving food and maintaining human health. This highly sought-after item, especially necessary where it was scarce, was salt. Cities like Timbuktu, Gao, and Djenné were key centers where this trade took place, largely due to the activities of trans-Saharan traders.
Both gold and salt were essential commodities for the Mali Empire, with the former being sourced from regions south of the Sahara like today's Ghana and the latter mined from places such as Taghaza. The salt mines in the desolate Saharan desert provided salt that was almost as valuable as the gold itself. The gold-salt trade was crucial, and the Malian rulers leveraged this by imposing taxes on these trades to enrich the empire, which further led to political stability and military strength.
In addition to gold and salt, other goods were traded, which included ivory, copper, and slaves, but for the specific trade exchange in question, salt was the primary item received in exchange for gold dust, which affirmed the economic foundation of the Mali Empire.