Would they really refer to Dragons as Beastmen? Seems like that would be a demotion for a Dragon...

I'm incline to speculate that maybe the Gnath are allied with Garlemald... They seem to be polluting the area with fumes (their territory seems reminiscent of Bluefog and the Ceruleum Processing Plant), perhaps they managed to strike a deal with the Garleans to supply them with resources... Giant and icy kind of fall off the table, but they're the only new beast tribe we seem to be getting "up north", unless you count the Vanu Vanu, but they seem to be skybound, rather than northward.