Why did African kings sell slaves to the Portuguese and the dutch?

African kings sold slaves to the Portuguese and the Dutch primarily for economic gain. They engaged in the transatlantic slave trade as a means to acquire European goods, such as firearms, textiles, and other commodities, which were valuable in their own societies. Additionally, the demand for labor on plantations in the Americas created a lucrative market for enslaved individuals, incentivizing African leaders to participate in the trade. This complex interaction was shaped by both local power dynamics and the broader forces of European colonial expansion.