Final answer:
The expansion of the slave trade starting in the 1500s can be attributed to the increased demand for slave labor in European colonies in the Americas and the availability of firearms and goods from European powers. This led to powerful African states emerging, which traded captives for goods from European traders.
Step-by-step explanation:
The expansion of the slave trade starting in the 1500s can be attributed to several factors. Firstly, the demand for slaves increased as European colonies in the Americas started to rely heavily on slave labor, particularly in the cultivation of crops like sugar cane. Secondly, the availability of firearms and manufactured goods from European countries like Portugal, Spain, England, France, and the Netherlands made them attractive trading partners for African kingdoms engaged in the slave trade.
These European powers obtained slaves by trading with African kingdoms along the western coast, who captured and sold individuals to meet the demand.
The economic benefits of the slave trade led to the rise of powerful African states like Whydah and Dahomey, which enriched themselves by providing captives to European traders in exchange for goods.
The expansion of the slave trade had a profound impact on African societies, militarizing states and reorienting their trade.