Why is there empty space between Demacia, Noxus and Freljord?

I am in love with the new map as it answers/explains some questions but it also poses new ones. The one I am most interested about is why is there a huge open space in the triangle formed by Demacia to the West, Noxus to the East and Freljord to the West. I understand that the Freljord stays in the icy regions so it is too South for it and Demacia might be too peaceful to go and conquer everything. My question is why hasn't Noxus occupied the area, they seem to be all for conquering as much as possible even going East to Ionia, South to Shurima and even South of the above mentioned area. Maybe there would be a story regarding the place? Maybe a Demacia vs Noxus event or the Void finally breaching into the mainland?

Tell me your theories- my best guess is that they will (I really hope so) make a huge Demacia vs Noxus event for the area or that the Void will come out of there starting the new world war (Rune wars style).