There has always been slavery inside Africa.
(Sadly slavery is still in Africa today.)
Europeans sold goods that the kingdoms wanted.
The kingdoms kept pushing further and further into the interior.
This created a continuous cycle.
Whites were sold into slavery in Africa also.
(They were captured from barbery pirates in North Africa.)
Besides avoiding plagiarism, documentation provides a paper with PROFESSIONALISM.
Answer:
passing a series of neutralityy laws
