Hey, hey! Another Reeve fan! It's always lovely to be reminded that there really are others out there.

Anyone else want to think we're just seeing one small portion of the world and there are whole continents out there that just aren't on the map?

I think that in some cases, that's very possible. In others... not so much. The other thing to remember is that on at least some of these worlds, they have been conquered by an almost global culture at some point, often in the near-recent past, and it could be that the language and currency are simply left-overs from that.