[Edi]

Yes, the RMG in Dom3 is capable of creating 1500 province maps and possibly even larger numbers of provinces. That's only graphics with white spots and a text file.

It's an altogether different matter to run a game on that map, since that goes right into the performance parameters and other limitations of the game engine.

Much like if you had an assembly plant that could construct any kind of vehicles weighing up to 20 tons and had an exit ramp off the assembly line rated for 8 tons. Sure, you can build a 20 ton vehicle and as soon as you try to drive it off the line, things start breaking, so you're practically limited to 8 tons.