Slavery was ancient culture,You must have seen or heard stories about Gladiators of Rome.1400 years ago they were every where, and there was no way to simply stop the system at once. If you read Quraan it has discouraged slavery and mentioned rewards for those who liberate slaves. When there was a custom, that a man can have a slave girl and have sex with her, islam mentioned it is disliked. In fact there is a famous quote from the prophet Muhammed, that any man who brings up a slave girl, educates her well and then gets her married to a good person, he will be rewarded with paradise. So wake up and ponder!!
