I think it's great slave farms in Southern Mordor, around the inland sea of Nurnen. http://www.glyphweb.com/arda/n/nurn.php http://www.glyphweb.com/arda/n/nurn.

I think it's great slave farms in Southern Mordor, around the inland sea of Nurnen. http://www.glyphweb.com/arda/n/nurn.php http://www.glyphweb.com/arda/n/nurn.php (There may also have been farms in the East that I'm not remembering. The East was definitely under Sauron's thumb, although perhaps not so firmly as he would have liked.)