Remnant is probably the word you're looking for, Kristoffer.
Vanarus seems to me to be as KO said, a nation ruled by Vanir who came and conquered the lands of the Rus or assumed leadership through trade influence. It's what I first thought when I heard the name way back when. That would be a very close historical parallel to the Vikings who sailed east along the rivers and established fairly significant outposts in Russia in the first millennium, around 800-1000 AD.
So EA (or MA, depending) Vanarus would be something like an amalgamation of Vanir, the Rus and Finland circa 1000. When you look at the Vyedun and Vyedma units that are already included (but currently not used) in the game, they are
very much like a mage or shaman in the Finnish tradition would be. Finland has historically been a battleground between Sweden and Russia and there has been very much a mixing of influences from both directions here, just that we speak a language which made it very, very difficult to annihilate our pagan beliefs (it did eventually happen, but there is a lot of data available because it disappeared so late).