Slavery has not...not...stopped. Girls are being trafficked as sex slaves here in the States as well as throughout other nations. Mauritania in Africa still has black slaves, owned by black slave owners. Boka Harum has kidnapped dozens of school girls and "married" them against their will, which is to say made them slaves.
Slavery is well documented in the OT bible; Moses for example freed the slaves from the Pharaoh. And in war, they took no prisoners back then except to use as slaves. The rest they simply murdered, man, woman, and child.
Human kind can't stop slavery any more than it can stop war. They are both natural animalistic conditions for humans. The predilection for slavery and war can only be controlled, not ended. So we put safeguards in place to prevent both, but they are imperfect safeguards at best and wars and slavery continue to happen.