The Norse, as it seems, are competing with the Inuit for a spot as the 'arctic' climate, and it's generally believed that they hold too much cultural similarity with the Normans, who are descended from Viking conquerors in France. However, I'd make the case that by the 11th century, while Normans were effectively a classic God-fearing Western European peoples, some pagan Norse societies were still in their hayday - the 11th century saw the (short-lived) colonization of Canada by pagan Norse settlers, and most of Scandinavia was not effectively Christianized yet; Denmark would be the first to have a leader convert to Christianity in the early 12th century. This unique environment could create a very interesting village-building settlement, with the settling down of raider viking-types into stable, civilized and advanced settlements while maintaining unique Viking traditions. Town halls could be a Mead-hall for the Jarl's martial settlement, a Thing for the Thane's agricultural settlement, and a Asatru temple/burial mound for the Volva's religious settlement. This'd make the Norse the only culture to have a female settlement leader as well. The religious settlement could even host a small mission and a priest to represent the growing Christian sentiment in the North. Overall, I feel there's a lot that could be done with the Norse as a culture.
Which brings me to my second point - choosing them over Inuits, because Inuits have a great deal more overlap with a second unique culture that could be added - Northern Native American tribes. Inuit culture as a whole shares a great deal of cultural tradition with other northern native american tribes of the modern U.S., such as building totem poles, shamanistic, animalistic religious rites, an inherently nomadic and hunter-gatherer lifestyle, and the use of collective, ritual dances and music. Ironically, some traditions of the two even overlap with tribal elements of Norse-Germanic culture, such as the building of burial mounds for respected leaders. If Inuit culture is added in, it removes the possibility for both Norse and Northern Native cultures as distinct cultures due to its geographical overlap with the Norse and its cultural overlap with the Northern Native American, whereas if Norse and Northern Native are added it's two completely distinct cultures in terms of geographic space and cultural-religious identity, which would seem to add a lot more to the mod.
Anyway, that's just my two cents on it. The mod doesn't even really need any more base cultures, quite frankly, but I do think some more tribal societies (and islam/african paganism but that's a completely different point) would be interesting. If you ever do consider adding in more as core cultures to the mod, I hope you'll keep these points in mind! Would love to interact with Native Shamans or Volvas.
