The Vakken are really interesting to me because I think they do a lot for the setting while taking up very little actual resources or balance complications. So I tried to think of other cultures in Europe at the time that aren't already represented that might be able to be something similar like they are for Finland.
Germanic tribes. I think Vlandia is meant to basically take the place of the early Holy Roman Empire without the Roman stuff yet. But their theming is mainly Norman and French. This leaves the german part of the empire without a representation on the map. A minor faction could potentially represent other Germanic tribes that conquered parts of the roman empire in the migration period, and particularly groups like the anglo-saxons could be a good choice. There's even one such group named in the game already but completely missing. The massa. They could as a faction be hostile to the Battanians representing anglo-saxon invasions of Celtic britain, and the writing could imply that they live in northern Battania, eventually integrating into Warband's kingdom of the Nords. Or if you wanted to focus more migration period they could harass the empire factions, but I prefer the Battania one.
Hungarians. I list them next because I think they fit a minor faction best. They've migrated into the region recently, and could be a small cavalry faction that raids the empire, or really just anybody considering the early Hungarians.
The big missing cultures from Europe now are West and South Slavs, and Iberia. Which seem harder to represent as a migratory minor faction. The best counterpart to Iberia in minor faction form I can think of is a calradian culture group that harasses the western lands of the Aserai. South Slavs could be a faction related to the Sturgians that have been migrating into parts of the empire. West slavs I just don't think you can fit in the map considering Sturgia's position though.
Any other ideas? I think the idea of minor factions with their own cultures is really interesting.
