Outer Tilog a power? Man, things have changed. The only things I remember from it are nearly dying again and again, and requiring Tom's intervention to prevent that (townsland as capital).
Realms rise and fall. Sometimes many times. I don't think any realm on the Colonies has a geographical advantage, not a major one at least, the continent is pretty round, the cities pretty diffuse. If a set of realms dominate, it's because they've got the manpower and the know-how to do so, and so their position of power is well deserved. Especially if said realms came from so low.