I always felt the orcs represented those people, especially the children taken as tribute from every Christian village and town across the Ottoman Empire, especially in the Balkans ( Serbia mostly).
These youngsters were taken by the empire and used as Janissaries(soldiers) or male or female members of the Pashas'/Caliph's harems( they always had a "boy-thing" going on as well).
They were taught to hate Christianity and to kill them with great passion. They were instrumental in the Fall of Constantinople...they were ruthless and brutal.
Serbia fell to the Ottomans in 1388, I believe...Constantinople in 1458. The Ottomans has quite a while to steal children and turn them into "monsters"...killing machines for islam....Or sex toys for their rulers.