The Viking Age
Norse raiders in shallow-draft longships that could cross an ocean and then row up a river appeared off English monasteries and, for two centuries, wherever water led. But raiding was the smaller half. They settled Iceland and Greenland, reached North America around 1000, founded Dublin, took York, ruled Normandy, and rowed the Russian rivers to Constantinople and Baghdad to trade furs and enslaved people for Arab silver. Arab silver coins turn up in Swedish farm fields by the tens of thousands. They were a trade network with a reputation problem.
Large movements of peoples — pushed or pulled — reshape the societies they leave and the ones they enter.