The EN World kitten
I recalled the Moonshae invaders, but presuming my memory was correct, they didn't play a very large role in things (though to be fair, my impression of the Moonshaes is largely formed by the first books, where the rest of the Faerunian pantheon really wants in there for no reason that I was ever able to figure out). Likewise, the Rashemi strike me as an example of the difference between barbarians and full-on Viking analogues. (I'd say the same for the Greyhawk tribes you mentioned, but I'm not very familiar with them.)FR had specifically fantasy vikings who invaded the Moonshaes and the short eastern europeanish Rashemi berserkers.
Greyhawk had the Snow, Frost, Ice, and Hold of Stonefist kingdoms as the explicitly fantasy viking analogues.