no mate, **** history, check the Warband lore and you'll understand better. Sturgians are the precursors of both Varangian and Nords (by mixing). Sturgians mixed with invading Nords, and later on Nords made a full blown invasion taking northern calradia and mingling with it's peoples. In WB Nords are almost pure, but a bit mixed with Battanians and Sturgians. Remaining Sturgians mixed with Battanians and became the Varangir.
Swadia formed out of Vlandia, while Rhodoks are an offshoot of Vlandia that don't make much sense, though in Warband there are some lame explanations.
What baffles me is that by following WB lore, that means both Sarranids and Khergit are part of peoples that basically dominated the entirety of the Empire lands (which's irritating, at least to me). The most probable outcome would be that half Empire would be taken by them while the other half would either become something else or be taken by other factions/cultures.
If we want more historically based BL, then they'd have to scrap WB entirely, Vlandians which are mostly "Normans" would have to be geographically located in a different area, never really coming in touch with Sturgians, Khuzait or Aserai. They'd have to have a domating "french-like" culture near them, Battania would have to be in a Island close to Vlandia, Sturgia would have to be wide-spread in wastes with little to no access to shores, Empire would have to have it's "capital" in a strategic choke-point with shores (big port) akin to Constantinople, Aserai and Khuzaits would have to "surround" empire territory sharing borders between them (it's barely like that, they don't actually share borders between them, it's more like they are both between a tip of Empire territory). Rhodoks are kind of the "Italians" so they should be a "proto-rhodok) at the south and not border Vlandia. Maybe even have their own kingdom around that Volcano near Rhotae, but with tons of shores. Aaaaa, I think you get my meaning.
And we'd still be missing a German culture, a Slavic Culture, a Scandinavian Culture (Nords are not in the game), a Finnish Culture, and a French culture (as I've said), that to give sense to the Geo-Cultural base of the game alone. Because Normans cannot exist without French + Scandinavians, Kievan Rus cannot exist without Slavs + Scandinavians, Rhodoks are basically Italians mixed with something, so on so forth. We either embrace TW's lore or it's simply impossible to make heads and tails of this