Until the rise of Islam and the contemporaneous Arab conquests, there was a tacit understanding across most of the Europe and the Middle East that while it was quite all right to make slaves of those belonging to other nations, it was not really the thing to enslave one’s fellow countrymen. This distinction was observed in most cultures. With the coming of Islam, nationality was no longer the crucial point, but rather religious faith. Mohammed, the founder of Islam, was not initially opposed to the keeping of slaves. He bought and sold slaves himself.
