Yeah he can, since that's the whole point.
Indeed, it is the point. The war was not Sirion standing up and saying "Hey Avamar, we're gonna kill yer ass, just because we feel like it." There was a continent-wide war, and Avamar was a realm on one side of it. Too bad for them that they just happened to be a tiny little thing, two regions away from the Sirionite juggernaut's capital.
Also: Kalmar Islands was taken over by former Avamarians, and some others. When Perdan and OR tried to get rid of the rebels and hand the realm back tot he original government, the rebels split off Kalmar city into Avamar Selective. Perdan wiped out KI, and OR/Sirion wiped out AS. The new realm of Obsidian Islands was then formed to reintegrate the flotsam (err... "islands") that nobody really cared about.
