The Africans themselves - Islamic ( Arab ) slave raiders - were the most prevalent contributors to the trade. The loosers in inter-tribal wars being sold off into servitude. The West ( Christians, British and American slavers ) did their bit too. But even prior to western contributors Africa was not a benevolent environment, climatic or tribal. More recently the population increases have been such as to negate any progress in the civilian environment, religious fundamentalism limiting any progress in birth management.