I don't want to sound a smartass but Mongols and Huns did apply slavery. Gengis Khan was a slave before he went on his greatness road. Also Chinese employed slavery for a long while as well. I slightly think that there might have been also something similar to slavery in the arabic world of the era, possibly with the turks of the ottoman empire, not sure.
So medieval times did see some slavery around the world.
So medieval times did see some slavery around the world.