What source of income did the majority of the african countries depend on for their prosperity?

mining

conquest

trade

fishing

The answer is: Trade

The african countries had a large number of natural resources (such as oil, gold, iron, copper, etc) . But very few of them had develop their technologies enough to convert these natural resources in to usable goods.

Because of this, the majority of them still overly reliant on other countries through trades in order to fulfill the market's demand.