No, the Arabs at the time of Muhammad(saw) were not traveling to mainland Africa to trade slaves at the time. It's easy to say today slavery is evil, immoral etc. , yet when I asked you "Are you more moral than Jesus(as), Paul, Aristotle, Plato etc.. ", you evaded the question. Perhaps you already know answering this question from a historical perspective is different. Even if you answer 'Yes', I'm sure if you lived in their times, your views (or mine) on slavery wouldn't be the same as it is today.