Slavery has been around forever, sadly. It started before even written records, and was present in the first societies in the Middle East. Babylon and Egypt, as well as other areas, are famous for their slave societies.

I think if you're talking about Europe, the first people there with slaves were the Greeks. they were famous for their slavery practices. they took them as prisoners in war campaigns and then sold them when they got back to greece.

this practice was repeated in Rome and then it spread to pretty much everywhere.

i just read up on the wikipedia article on slavery. apparently after the fall of rome slavery disappeared for the most part in europe and then came back during the renaissance. this was because of the nostalgia for the 'good ol days' of rome and because of the expansionist efforts of colonialism.