I feel like this is common in most (at least western) empires. Vikings from Sweden would take over territory as far as Poland or even Italy and recruit new sol

I feel like this is common in most (at least western) empires. Vikings from Sweden would take over territory as far as Poland or even Italy and recruit new soldiers. Eventually some of them would end up in warrior style graves. What's actually more interesting in my mind is that they didn't bring people back, and so the gene pool in Sweden remained more or less unchanged