Forgotten Realms <3
I don't have my book-of-love here at the time (friend has it), but after a quick glance to Forgotten Realms wiki
, I can say my first thoughts were mostly correct. Oh sweet, I found the scanned version on my comp...
There isn't exactly a viking inspired place, but the Cold Lands
are your best bet (FRCS page 106). I'd recommend Vaasa, Damara and northern Narfell. You could also try Icewind Dale
, but there's not a whole lot of info there (beyond the Icewind Dale books ofc). There's also some vikingesque people in Moonshae Isles
(FRCS page 148) called the Northlanders, but that takes you kinda away from everything else (unless your party can quicktravel, or you like to set the whole campaign there). The Northlanders are descendants from Ruathym raiders, so that would be closest to the classic vikings (my guess, also no info on the island, so you can shape everything yourself).
If you can't get a hold of the FR Campaign Setting, and feel like you need more info, pm me for some details.
And what on earth are NorthWest Isles?