First Ice War
Military action
Ice Kingdoms attempt to expand onto the unfrozen lands, triggering war.
Ice Kingdoms formed long ago, but were busy for centuries with purging internal dissidents (many still remained). It was also a target of relentless raids from Niflheim, Dragarian Isles and Lomar.
It finally attempted first, still quite meager attempt to expand that was later on called First Ice War. Attacking Lomar, Niflheim and isle of Gothera simultaneously.
They were ultimately pushed back after several years of fighting.