So we have the Holy Roman Empire, England, Scotland and probably Norway (or a butchered Kalmar Union.) The previous giant Empire seemed like the Mongol Empire, but I don't think they got to Scandinavia. So the author probably mixed both, sprinkled some author power on it and went with that.
Shaltha Kingdom is Norway and some of Sweden and the Kilhina Kingdom is Finland. But Suomi is in Finland, so it's weird that that port city is in the Shaltha Kingdom.
The HRE is in Poland for some reason and the Yeesus City State is in Russia... They could have gone with the Teutonic Order or something like that for the Yeesus City State.