The Shoshone Empire
The year is 2000. The Shoshone Nation is a mighty superpower, occupying the entirety of both South America and Australia, as well as the entire western coast of North America, and the southern tip of Africa. They're a somewhat puzzling nation, staunchly neutral in every military conflict, yet no one dares to challenge them because their scientific achievements not only exceed every other nation on earth, they also exceed the imagined possibilities of other nations' science fiction. Spies are almost always immediately caught by Shoshone intelligence agents. And despite their neutrality, everyone who challenges them disappears so swiftly that no living person knows what it's like to fight against Shoshone forces in battle.
Unlike most neutral isolationist leaders, however, Chief Meadow Whisper seems quite eager to impose her will on the rest of the world. The Shoshone Nation started a world congress, which later became the UN, but the Shoshone delegation always gets exactly what they want, effortlessly outvoting everyone else combined. They're a cultural powerhouse too, dominating every artistic field, with broadcast towers on every continent; no matter what you're watching or listening to, the gentle tones of Shoshone flutes won't be far away.
Will the Shoshone Nation ever loosen their grip on power? Will anyone ever say "no" to the Shoshone Nation and live to tell about it? Will Chief Meadow Whisper continue to be satisfied with simply designing terrifying future weapons, or will she want to actually use them someday, even if no one has any hope of posing a threat? If she decided she wanted to occupy another nation, for whatever reason, would anyone be able to stop her?
The year is 2165. Elders keep talking about these things called "other countries", but no one actually remembers them. We're all Shoshone, and we always have been, right?
Honestly, the past described by those elders sounds pretty bleak anyway; "other countries" seem to come with differences of opinion, which leads to people killing each other (they called it "war", I think). Most of us can't remember the last time we heard about the military killing someone, despite their utterly massive size; the younger generation doesn't remember it at all. Chief Meadow Whisper even proudly proclaimed that she had eradicated barbarians! What a wonderful time we live in!
Of course, no one has actually met a barbarian for countless generations, if they ever have, but why would we want to? They're obviously soulless monsters. There are occasionally rumors that they were just regular people who didn't like The Great and Powerful Chief Meadow Whisper, but those rumors are so ridiculously far-fetched that only the most fringe weirdos would do anything except laugh.
I have to admit, though, it does sometimes feel a little weird that Chief Meadow Whisper monitors every square inch of the planet at all times. I'm pretty sure that hasn't always been the case, especially since our military is doing the surveillance with ships and robots that seem ill-suited to the task. She even has giant robots patrolling the snowy tundra, since that's where barbarians used to set up camps (probably because it's the only land that doesn't have anyone living on it; who would want to live in the cold anyway?). And the entire southwestern part of Australia Island has nothing but troops stationed and waiting to drop into anywhere on the planet at a moment's notice.
But hey, we're safe, and we don't have to worry about things. That's the most important part. And our children won't even remember what it's like to worry about what's going on in the world.