Although it is not generally known, slavery was and had been ubiquitous in Africa for centuries. The slaves sold to cross-Atlantic slave traders (although the numbers were admittedly big) were only a small part of the number of Africans enslaved and kept as slaves by other Africans.
Not many African slaves were sold to colonists. The only sizable number of colonists before 1890 lived in Cape Town, and they mostly used Asian contract labourers who were considered more efficient and hard-working. The colonists entering Africa afterwards came in long after slavery had already been abolished.
they were captured in war
The slaves that West African slave traders sold to Europeans were usually captured in war.
The slaves that West African slave traders sold to Europeans were usually captured in war.
The slaves that West African slave traders sold to Europeans were usually captured in war.
The slaves that West African slave traders sold to Europeans were usually captured in war.
The slaves that West African slave traders sold to Europeans were usually captured in war.
The slaves that West African slave traders sold to Europeans were usually captured in war.
The slaves that West African slave traders sold to Europeans were usually captured in war.
The slaves that West African slave traders sold to Europeans were usually captured in war.
West African slave traders
European slavers did not capture the Africans they transported themselves, but bought them from native slave traders.
European slavers did not capture the Africans they transported themselves, but bought them from native slave traders.
They were usually brought over by white slave traders during the migration west. Some black settlers were known to travel in that direction though.