>>513045000
Traded with Rome.
Did mercenary jobs for Rome.
Rome fell.
Read Beowulf, it details some of the chaos going on when the new swedish king tries to downsize government and gets a rebellion instead.
Then you have bored groups of Navy SEALS specifically trained by Rome to kill legionaries.
And they spent years in enemy territory, they weren't randos on boats. They had all food and logistics with them.