Ghana, Mali, and Songhai were known as the Kingdoms of

Gold and salt

Explanation:

The kingdom of Mali is one of the most important kingdoms in Africa in the sub-Saharan zone that develops parallel to the Middle Ages in the west. Together with the kingdoms of Ghana and Songhay, they represent one of the most important consolidations of the central culture of Africa, in relation and in contact with Islam.

In West Africa during the medieval period, salt was sold for gold. Although salt is currently readily available today, this was not the case in ancient times. In the past, salt was difficult to obtain in certain parts of the world. This means that the salt producing areas had a valuable trade item, one that they could trade for gold. In medieval West Africa, salt led to the development of trade routes and brought great wealth to the cities and states they passed through.

Gold and Salt (or Salt and Gold)

Ghana, Mali, and Songhai were all kingdoms from West Africa and they were known for trading gold and salt with European countries. These three kingdoms controlled the trade which is why they became so powerful.