My point is that people would probably not be bothered if Shapur or Yazdegerd was chosen as the Persian leader in a future incarnation, if Islam was the default AI-favoured religion, or if Hecatompylos or Nishapur were part of the Persian city list, because in-game Persia can legitimately represent any part of Iranian history. It represents the Achaemenid more thanks to popular recognition of this part of Persian history than a conscious effort to be self-consistent, I suspect: leaders like Darius and Cyrus are well-known where Parthian and Sassanian leaders aren't, and the Immortal is the first military unit people would think of in association with Persia.