User blog comment:BorosPaladin/The Shadow Isles' History/@comment-5571637-20121029102207/@comment-4834593-20121029151052

It's, to be exactly, these things:

Noxus vs Demacia

Noxus vs Ionia

Piltover vs Zaun

Part of Shadow Isles vs other Part of Shadow Isles

I might have missed a few though. Don't know about relation between Frejord and Noxus, for example, nor do I know how Bilgewater does past it's borders.