Right you are, Joe. I suppose I believe that Middle Earth actually existed. Tolkien sure has me convinced.
I did take some time to research online -- the Nubian angle is true, but I lost that link.
Reading between the lines of Jeremiah's post, I suppose the fact that Persia is now Iran could prompt a filmmaker to throw in some not-so-subliminal barbs regarding Persians. Every person I met from Iran after the fall of the Shaw (they seem to swarm into Newport Beach, CA when I was in business on the Peninsula) was insistent that they were Persians, not Iranians.
Even though you've pointed out they are from Asia, I don't get the connection of racism as their ancient heritage is a mix of aboriginal Caucasians and Asian peoples as far away as China, as well as many other ethnic peoples beginning in Southeast Asia. Iranian is a term for all these peoples from Eurasia to China.
So the Xerxes in the film may be off track according to what he likely resembled from art of that age but I can see where they got their inspiration for their kinky, new age revisionist Xerxes (who looks like he belongs in a Gay Pride Parade). I think it's hilarious that anyone gets worked up over it. Lighten up.
http://en.wikipedia.org/wiki/Iranian_peoples