Analysis of information sources in references of the Wikipedia article "مسلم دنیا میں غلامی کی تاریخ" in Urdu language version.
Historian Roger Botte estimates that Arab slave trade of Africans until the 20th century has involved from 12 to 15 million persons, with the active participation of African leaders.
ln later times, for which we have more detailed evidence, it would seem that while the slaves often suffered appalling privations from the moment of their capture until their arrival at their final destination, once they were placed with a family they were reasonably well treated and accepted in some degree as members of the household. In commerce, slaves were often apprenticed to their masters, sometimes as assistants, sometimes advancing to become agents or even business partners.
