Parthia is a bit more difficult than Scythia or Armenia, IMO. Mainly due to a very poor starting economy, but more importantly, no place to go to improve this situation except Seleucia.

Armenian lands are just as poor, and the vast steppes of Russia are in the same shape with the added penalty of simply huge distances to travel. That leaves only the Seleucids.

By itself, it isn't such a big deal running circles around hoplites and dealing with the pesky militia cavalry, but coming down out of the mountains will bring you into combat with the Big Yellow Machine sooner or later, and my experiences were sooner.....and long before I could get ellie's and cats.

I'd rather play Numidia than Parthia, even though HA factions are my favorite