The truth is, all those Vikings, Romans, Saxons and whoever, were goin into places which was not theirs and taking things which did not belong to them. On side of that they often murdered locals, In my book its called invasion and theft. burlglary or robbery and finally murder. I understand people going into new places, seeking opportunities, but you knock at the door and say 'good morning', while those would rather welcome you with an axe in your forehead.