How many races or what races have been subjected to slavery other than Africans?

Now I've heard it said before that "RACE doesn't actually exist." That even though we all look different, in reality: "we are all ONE HUMAN RACE." That being said, I'll tell all who can read this the REAL TRUTH. That although our yokes are seemingly invisible to us, WE ARE ALL ON THIS PLANET ACTUALLY SLAVES. Hard to believe, I know. But research the matter yourself, you don't have to dig far. It's all right in front of you, hidden in plain sight. But in a way you're almost better off NOT looking into such matters and really just forgetting the whole topic. I guess ignorance really is bliss.