There's evidence that Pathian recruit Median infantry and Cadusii infantry against Marcus Antonius invasion. So why don't just create special urbanization phase for them to unlock these units. By giving the Parthians a special urbanization phase, we could turn a horse archer based civilization into a balanced civilization which incorporate both Medians, Persians and other ethnics in Persia. I am fan like who have always anticipated the day when the Sassanid become a playable civilization in both campaign and custom battle. i mean no ill will against your hope to make Sassanid as a playable faction but i hope both of us could see our long anticipated faction could become playable. As a new member of the forum, i hope i could see the game become a success that no other game could match, but after all, i am not the one who made the decision. Anyway i wish you good luck.