Final answer:
The distinctive aspect of the salt-gold trade was the use of salt as a valuable commodity and form of currency, traded for gold in sub-Saharan Africa. Salt caravans crossed the Sahara to trade with agricultural communities that lacked the mineral, with the powerful Mali Empire controlling and taxing the trade routes.
Step-by-step explanation:
What is distinctive about how transactions in the salt-gold trade were carried out is that, during the medieval period, besides other commodities, salt functioned almost like a currency due to its critical uses in food preservation and its necessity for human and animal life. Salt was mined from places such as Taghaza and carried in large slabs on camel caravans across the Sahara, signifying its high value, similar to gold, which was also a principal commodity of exchange. The salt was traded south of the Sahara where it was scarcely available, making it extremely valuable for agricultural communities that could offer gold in exchange, sourced from regions such as today's Ghana.
Trading was often facilitated by the indigenous peoples of North Africa through a network of trade from oasis to oasis, avoiding the risks of passing through the vast desert expanse. The Mali Empire played a significant role in controlling and taxing this trade, establishing a powerful empire that benefited from the wealth generated through the trade of salt and gold, which were stored in the royal treasury alongside each other.