I would buy Norsemen if Morder were to the North ("from the fury of the Norsemen, lord, deliver us"), but hordes of brutal attacks from the east do make more sense as Mongols or Turks, given that medieval/renaissance European horror of "Tartar" hordes attacking from the east. So the movies' error was actually in being a different kind of racist than the books intended, rather than in being racist at all?

Hmm... In the books, I always kind of got the impression that the Uruk-Hai looked basically like other orcs, except bigger.

Yeah, "orcs and goblin men," which confused me, because I was never clear on what the difference between orcs and goblins was, exactly, or if the orcs in the Trilogy and the goblins in the Hobbit were possibly the same thing (the Hobbit goblins I imagined as very pale, because they lived in caves).