As a western European when I hear the terms "master" and "slave" I don't think in terms of American history, I think of the Romans.
In Europe our history extends tens of thousands of years in the past, most children in Europe will start learning history from our cave dwelling ancestors, through Egyptian, Greek, Roman, Viking and finally the Middle Ages. Most of what Europeans learn about history and slavery comes from the Egyptians, Greeks, Romans and Vikings, all of whom captured, brutalised and traded in slaves.
One fact that unites these peoples in the early part of our history is that they didn't care whether you were black, white or Asian, if you were in the wrong place at the wrong time, too bad you're going on a long journey and your life is effectively over, you are and foerver will be a slave. The Vikings would raid monestaries in the North of England regularly to capture monks and ship them all the way to modern Turkey to be sold as slaves, monks were able to read and very valuable as slaves. The Romans and Greeks would capture anyone they liked who would not conform to the empire's rules.
So when I hear the words "master" and "slave" I think Roman and Viking raiding parties, capturing innocent men, women and children of any culture, creed, skin colour or religion, even those who were supposed to be protected by law.
I'd also bring to your attention the world of BDSM, which in recent years has moved to the softer terms of "top" and "bottom", or "dom" and "sub", however some still prefer the more possesive terms of "master" and "slave" in order to induce a more potent state of mind within the relationship. Soft terms like "dom" or "top" may not induce the same feelings, so referring to "master" or "mistress" make both parties feel stronger in the roles they've chosen.
"master" and "slave" are strong words, they have nothing but negative conntations but I'm getting sick and tired of objective words like this being erased from history simply because they're negative. You cannot remove all negativity from language simply because you feel personally offended by it in terms you have defined. Languages are rich and vibrant becuase of positive and negative words, they bring a language alive. While those term will be abused and they will be used to offend, simply turning your back on negative words and hiding them will result in a dull lifeless and generic language that cannot describe the world we live in.
Slavery continues to this day, we need the words "master" and "slave". Sexual and domestic slavery occurs still right around the world, it's happening right now most likely in the city you live in and you won't even see. We need those words until slavery is abolished and gone forever in any form be it people, animals or simple devices. I'll let you take those words when we no longer need them, but they describe important concepts of a foced relationship and they're still need to drive home the oppresive nature of that relationship.