Whilst I am more in favour of my original suggestion, to wit the purple citystate, and the brown nation being a small part of a larger empire, if folks want to play the brown nation;
The larger green nation would serve as a limiter to the brown nation's power; an overly aggressive policy might attract undue attention from their souther neighbours, who would otherwise be a gentle giant, content to fester in their own outdated bureaucracy.
I assume that expansion would be focussed towards the coast, hence the lack of anything barring barbarians (monsters) to the east.
If, in the end, we don't play as the brown nation, I think it would be better for it to be the corner of a far larger nation. More like this:
Playing a province controled by an NPC empire?
This is the kind of situation that will lead to this:
"Send a message to the emperor. We are at war against the city state of Hurrdurr. Some military support could be useful."
"[6] The emperor sends fifty units of infantry, twenty five units of heavy infantry, [...] and says hi."
In this situation, the entire storm coast and every mercenary it can muster rushes to the aid of the city state of Hurrdurr. But yeah, still not as entertaining as more small-scale combat.
E: Also, how the flying fudge is that brown. I'm calling it brown because everyone is, but seriously. It's a pale, dirty orange.