What did West African kings became powerful by controlling this?

West African kings became powerful by controlling trade routes and valuable resources, particularly gold and salt. By managing the flow of these commodities, they were able to accumulate wealth and influence, which also allowed them to strengthen their armies and establish centralized authority. Additionally, their control over trade facilitated diplomatic relations and cultural exchanges with neighboring regions and beyond. This economic power was crucial for the rise of prominent empires like Mali and Songhai.