The Skraelings were an indigenous people of Northern American and were encountered by the Vikings of Greenland back in the 11th Century. The word Skraeling means barbarian or foreigner in Old Norse, and was the name give to what we think were the Thule peoples, ancient descendants of the Inuit.
The Skraelings and Norsemen were in regular conflict during that time. Its an unusual kind of force to pit against mainstream Dark Age armies but it should give gamer's the chance to try something different from the norm. Of course they would also be suitable to mix in with tribes from the French-Indian Wars too with little problem.