Islam and Slavery
It's generally known that The United States was partially built on slave labour of millions of Africans captured and deported to America. However this slave trade was dwarfed by the Islamic slave trade taking Africans from Africa to the Middle East which stole up to 20 million Africans and in many cases cut off their testicles and penises as well, a process not without dangers (60% death rate) and with unhappy side effects. Of course this occurred to white slaves as well, Islam is renowned for its lack of racism.
The East African slave trade also provided women for concubines and servants and of course a Muslim was entitled by sharia to the sexual enjoyment of his concubines, servants and slaves. That's his sexual enjoyment, of course, not theirs.
When the trans-Atlantic slave trade began in the 17th century the Muslims with their thousand year history of African slave-trading provided a fine example of Christian-Muslim international co-operation of the worst possible kind. Europeans took slaves south to the Americas and Muslims took slaves north to the Muslim empires. Slavery by Europeans was abolished by 1815 but it only ended in the Islamic world in my lifetime (well almost ended). Slavery of Europeans by North African Muslims was another long and successful trade and only ended in the 19th century with the conquest of North Africa by Europeans.