Answer:
because of gold and silver....? I think.
Explanation:
One thing was that a social class system was created. A bad thing would be that there wasn't much medical treatments. This meant people could die of simple things.
Just 3 reasons? ok then, they were unprepared for the desert climate, they had a poor reputation with the locals, and they were considered "devils" so no one wanted anything to do with them.
I believe it was slaves. From what I know, slaves were widespread all over Africa. I hope I helped.
