It's easy to understand why Cecil B. DeMille's 1956 Biblical epic The Ten Commandments had a principal cast made up almost entirely of white actors, despite being set in Egypt - it was released in 1956, after all. However, when director Ridley Scott mounted his own production of the Moses story, titled Exodus: Gods and Kings, quite a few heads were turned by the fact that the principal cast - which includes Christian Bale as Moses, Joel Edgerton as Rhamses and Aaron Paul as Joshua - was comprised almost exclusively of white actors.
Based on the trailers, it looks like Exodus: Gods and Kings gets around this issue by slathering fake tan over the actors' faces and calling it a day, but with issues of representation in cinema currently a popular talking point, Exodus: Gods and Kings has already drawn quite a bit of criticism over its whitewashed cast.
When asked in an interview with Variety about the decision to cast only white actors in the lead roles of Exodus: Gods and Kings, Scott was very blunt in his response, making it clear that he hadn't even considered casting non-white actors instead.
"I can't mount a film of this budget, where I have to rely on tax rebates in Spain, and say that my lead actor is Mohammad so-and-so from such-and-such. I'm just not going to get it financed. So the question doesn't even come up."
Tactless it might be, but Scott's response does highlight a depressing reality for non-white actors in the American film industry, when even blockbusters where the setting and source material essentially demand a diverse cast instead default to using all white actors in the main roles. Established franchises like Star Wars can afford to cast newcomers like John Boyega as leads, but Kingdom of Heaven is evidence that a standalone historical drama won't automatically draw in audiences just because it was directed by Ridley Scott.
With that said, it's not really possible to absolve Scott of all responsibility for the whitewashing of Exodus: Gods and Kings. Based on his response it sounds like he didn't even consider casting "Mohammad so-and-so" (a pretty derogatory term meant to encapsulate all non-white actors) in the lead roles, which kind of negates arguments about Bale and Edgerton being chosen because they were the best actors for the part.
Even outside of established franchises there's been evidence that blockbuster movies don't need big (white) Hollywood stars to perform well at the box office. In Pacific Rim, for example, the two heroes were played by an actor from Sons of Anarchy and, to mimic Scott's phrasing, "Rinko so-and-so from such-and-such." Meanwhile Ang Lee's Life of Pi, which got financed to the tune of $120 million and grossed over $600 million worldwide, was the feature film acting debut of "Suraj so-and-so."
Exodus: Gods and Kings releases on December 12th, 2014.