I assumed that was Persia over in Asia. Obviously not having played WoS, I have no idea whether that's a problem or not.

I'm certainly no expert on the period, but from what little I've read, one might expect a significant proportion of Greek mercenary infantry among the Persian order of battle. Apparently they started doing this pretty regularly not too long after the Marathon-Plataea period, at least in that part of their empire. In other words, the Persian armies might not be THAT much different from your own (assuming CA's representation is historical...which is a big assumption).