I would guess they came from a fictional England across the seas, maybe Balion (reminds me of Albion, it's only a few letters mixed) which could have been invaded/colonized by Nords from Jumne in the past kinda like the Viking age in the British isles? It doesn't make much sense for them to have come directly from Jumne since their culture is more "westernized" and we know the Nords are still there and there are mercenaries/adventures and nobles of Nord origin in Bannerlord's Calradia (mainly in the nobility of Sturgia and the Skolderbrotva mercenaries) and we also know the Nords will invade Calradia with a great army some time between Bannerlord and Warband to carve a kingdom from Sturgian/Vlandian/Battanian land.