What is the relationship of interaction to the rise and fall of Ghana Empire, Mali Empire and pre-colonial States?

The relationship of interaction with per-colonial States

Explanation:

Rapidly growing trade brought a lot of wealth and power to West Africa. The rise of the many empires in Africa began with the trading connection. The trade with other region earned the empires like Ghana and Mali prosperity. Ghana Empire became wealthy because of gold smelting. The empires rose to prominence through wealth from trade and maintained strong cavalry. A large army of Ghana helped to secure the borders, controlling minor revolts, and maintaining peace and order in the empire and neighbours. The Mali Empire rises as gold became the centre of the trans-Saharan trade.