Gold trade and kingdoms played an important role in the birth of the slave trade in africa. while slavery was common in africa, it became a lucrative commercial business when started buying slaves. african rulers encouraged this trade as it made them wealthier.

Europeans

Explanation:

The West African kingdoms and the gold and salt trade were big factors that resulted in slavery in the African continent. Lot of people that were from smaller tribes and were conquered were taken as slaves by the African kingdoms. The Europeans in meantime started to settle in the Americas and they needed lot of labor force for their large plantations of cash crops. The potential in Africa for getting slaves was noticed by the Portuguese, and soon the others followed, developing the slave trade, which brought in lot of wealth to the African kingdoms while the slavery was in existence.

they were all fought in the middle east during ww1