It occurs to me that there aren't a lot of actual nations in the Myth world, or at least not in my particular RPG-based version of it. Here's how I picture the state of things circa 2841 AE:
You've got the Cath Bruig Empire, which takes up most of the map of the known world. The Dwarven nation, the Ermine (home of the fir'Bolg), and Forest Heart (home of the forest giants) are only pseudo-independent of the Empire. The two former groups participate in the Imperial government and are mostly subject to Imperial law, and even the forest giants don't seem to have a problem considering themselves to be Imperial citizens when they actually bother acknowledging human civilization at all. The dwarves, fir'Bolg, and forest giants all seem to respect their own kings or leaders and the Cath Bruig Emperor as equal co-rulers.
Maybe these people genuinely get along with humankind, or maybe there's something nefarious and colonial going on here, like cultural imperialism or brainwashing or something, or maybe it's a bit of both. I haven't decided yet. I'd love to hear input from my players on this.
So what about actual, independent nations that are not part of the Empire at all?
There's the Drowned Kingdom of Yer-Ks, home to the amphibious, serpent-like Skrael. They aren't hostile to the Empire, but they're completely isolationist, so there's no diplomacy or trade going on between the Skrael and anyone else. The Empire and Yer-Ks just ignore each other.
There's Stoneheim, a dwarf-built city that is currently occupied by the Ghols and serves as their main city-state. They control some land around Stoneheim and probably some places off the map to the east, but Stoneheim is basically their actual nation. They're in a state of total war with the Empire and the dwarves, so there's no diplomacy or trade going on there at all.
There's the Blind Steppes, which is ostensibly Trow territory, but is mostly inhabited by the mauls, who are a nomadic people and don't really have what the Empire would consider a proper, unified nation. Other than mercenary work, there's no real commerce or communication going on between them and anyone else.
The trow refer to their nation as Avernus. (In the actual computer games, I'm not sure if Avernus was meant to be a city, a region, or what, but I'm using it as the name of a nation in my game.) At different times, the trow have been everything from complete enemies of mankind to neutral observers to just oblivious co-inhabitants of the same world. But every since the Soulblighter war, the Trow have taken on a new role: reluctant allies. They do not bow to the Empire, but they acknowledge them as a separate, sovereign nation, and have agreed to co-exist peacefully. This is a huge step up in terms of human-trow relations, but trade is almost unheard of between the two nations, and the trow are in practice almost as isolationist as the Skrael. They do occasionally talk to the other races, at least.
The Untamed Lands are the places beyond the eastern edge of the map. There are nations out there, scattered between the great swathes of howling wilderness, or perhaps even beyond the wilds in some distant civilized corner of the world, but such places are unknown to the Empire. As far as the humans, fir'Bolg, and dwarves know, it's all just deadly, primeval, uninhabited awfulness. Not that they wouldn't like to settle it, since they can always use more farmland and other resources, but expeditions have proven almost universally unfruitful throughout their known history. Plus, that's where the forces of darkness usually come from when they march on the known world, so there must be some powerful evil out there.
And then there's the Remote Lands, which are analogous to the Americas in that they're off to the west of fantasy pseudo-Europe across an ocean, and said pseudo-Europeans have newly discovered these places and are starting to colonize them. But other than that (and some similarities in climate, ecosystem, etc.), they're very different from Early Modern America because the idea of just making the Myth world a thinly-veiled copy of Earth, with a fantasy America, fantasy Africa, fantasy Asia, etc. seems boring and lazy to me.*
And so the Remote Lands are just mysteriously empty of sentient/sapient inhabitants. Like, worryingly empty. No nations, no cities or towns, no tribes or nomadic peoples, no one. If anybody's home, they're either hiding or otherwise imperceptible to the colonists. There are plenty of monsters, though. And strange, unnatural phenomena. And clues that these lands were not always uninhabited.
Bottom line: In terms of sovereign nations, the Empire only has Avernus, Stoneheim, and Yer-Ks to deal with. Imagine if the Roman Empire or Ottoman Empire was only surrounded by three other countries, a small number of nomads, and a bunch of no-man's land. Odd, right?
Now, none of this is meant to imply that there isn't anything interesting, important, or gameable going on in the Dwarf Kingdom, the Ermine, Forest Heart, Yer-Ks, Stoneheim, the Blind Steppes, Avernus, the Untamed Lands, or the Remote Lands. This is just the current political situation in Myth, post-Soulblighter. On the contrary, I think we could get a lot of mileage out of the Empire's ignorance of the wider world. What's out there? Why don't you go and find out? I'm sure there will be monsters to kill and stuff to take, and plenty of wider ramifications to whatever you find or do in these places.
But I'm also interested in the implications of having an Empire exist almost in a vacuum, with nearly no other nations to contend with. What would such a culture be like? Can I get anything gameable out of this concept, anything that my players will find interesting to interact with?
I don't have any solid answers yet, but I wanted to talk about the things I'm pondering about this campaign world at the moment. I want to explore the differences between this fantasy world and the real, historical one. There's no way such a weird (from my point of view) political situation wouldn't have some weird effects on the Empire's citizens.
*I have no problem incorporating non-European cultural ideas into a setting, of course, but right now I don't want to just copy-and-paste real-world civilizations onto a fantasy map any more so than I've already done. Yes, fantasy Europe is overdone, but I'm kind of stuck with it if I'm going to use Myth as a setting. And I'm fine with that, because I enjoy this setting. That said, campaign settings like Empire of the Petal Throne, Yoon-Suin, and Red Tide are awesome in part because they're not just more of the same (i.e. slightly altered takes on Middle Earth or King Arthur's England or Narnia or whatever) and in part because they're just interesting and well thought-out worlds. To be clear, I'm not anti-European fantasy so much as pro-Any Culture fantasy.