“First off, you have so many eras. You talk about them coming over the land bridge, but then that’s very recent. In general, people are migrating everywhere. Think about it in terms of Earth. Where were people, and how did they move, over a thousand years? Now multiply that by six eras! Shit happens here, in Eorzea, a Calamity, it gets too hot, it gets too cold; people move away to a place that’s better. They break off there, and come back.
So the Fifth Umbral comes and ice starts appearing and disappearing all over, and you can get to and from different places that you couldn’t before, sometimes; even the southern islands where the Lalafell are from. The Miqo’te are coming back from Ilsabard and they’re coming back from Meracydia, but they got there in different time periods. They converge on places that are rich in the aether, because that’s what it’s all about. Places that have more aether are going to be more lush, be better for growing crops and surviving, and there’s going to be animals.
And we explain that; everybody ends up converging in Eorzea because that’s where the best aether is and that’s where you’re going to have the best hunting. The Miqo’te especially being hunters are going to follow where the best animals are and that’s where it’s all rich. You go beyond that and things start losing that. There’s still aether everywhere in the world, but it’s the rich places where people converge. It’s like the Mesopotamian thing where you have the two rivers there, the rest is desert, people are going to come back here, even if they get shut out by a flood, they’ll come back at some time.”