Yes yes, keep in mind, the movie was not based on the historical events, no where near it. Frank's novel is very loosly based on the events that actually happened.
The Persian Empire was actually quite beneficial to the growth of the area, and it's positive impact greatly outweighed any negative. They portrayed them in poor light in the movie. Someone's gotta be the antagonist, i guess. *shrug*
I thought the movie was pretty decent, worth the money.