Njeperz the red is a common topic for UrW players.
When it comes to Njeperz, people oftens mapping them to east slavic people.
I have a question that UrW is base on the iron age in Finland(Sápmi, in precisely), which is C1st~C5th. AD.(From C4th BC., If we count in Findless Age)
But east slavic people (Ilmen tribes then) was not waging war against Sápmi people until High Middle Ages IIRC.
However, germanic tribes like Saxon did lots "migration". It can be inferred migration not only happen in western Europe but north Scandinavia.
(Even in Findless Age, there was warlike Jastorf culture in C6th~C3th BC. in southern Scandinavia & north Germany.)
In Finnish, "Sima"(mead) is from Proto-Germanic *saima-.
"raha"(money) is from early Proto-Germanic "*skrahā"(squirrel skin).
In UrW timeframe we're all witness of this loanword adopted from Proto-Germanic.
Moreover, in-game item "Njerpeziläis Scimitar" have a *-äis word-final, which is similar to German word. (probably)
If he looks red, swims like a robber, and quacks from east, shall it be
communist slav?
BTW Polish "Niemiec"(German;foreigner, literally "one who mute(won't speak our language)")
make me think of Nje-perz.