In my opinion, it'd be better not to make so called competition for the factions at the outskirts of the map... I don't think one could seriously expect competition from one faction for starters, and I think it's one of the nice parts of the game, that you have factions far away from the world's centre that have to struggle a time agains the Eleutheroi first. Better to add factions to the factions in the middle of the map...more Greek cities or leagues, Belgae, perhaps cisalpine Gauls if that'd be historical, Kartli, etc.

I think it's far more interesting (to game of course) to witness conflicts between foreign powers just beyond your borders, and see your erstwhile allies or enemies recoil. It creates a political aspect, one must always have diplomats at hand near the homeland. Otherwise, it's also interesting to play for years against several different tribes (Eleutheroi), have a nice empire in your back when you suddenly bash with full power against the other factions...
If you, for instance, play as the Casse, then there's nothing about it of suddenly meeting the (p.ex) Eraìn... "Hell there they are...!"...nothing really interesting...