It's worth mentioning that the Transatlantic Slave Trade wasn't even the largest:
http://www.bbc.co.uk/religion/religions/islam/history/slaver...
http://www.bbc.co.uk/history/british/empire_seapower/white_s...
Taking millions of Africans and even one million Europeans as slaves doesn't quite mesh with the popular perception of Arabs as poor, helpless victims of Western imperialism.