We could create our own timeline whilst still following the canon of Runeterra.

Demacia is in constant conflict with Noxus, whilst Ionia remains a middle-ground (validty of this? If its our canon then it don't matter...) and a slow, turning rampant-growth in strength within the Shadow Isles that eventually threatens all three factions.

And then there's also the the Desert (I don't know remember the proper name, but it's Azir as the Pharaoh).