The peoples of southern Scandinavia were under near constant threat from the belligerence of their Christian neighbors. The Frankish Empire was being carved out at the point of a sword by Charlemagne's expansionist wars in the late eighth century and the North would have been feeling these social pressures at the time of the first raids. There is little to suggest the slowly expanding Viking polities ever felt entirely safe from southern assault even into the new millennium Scandinavian military endeavors almost always included an element of proactive defense alongside their more immediately mercenary ambitions.
This show picks up where Dan's Thor's Angels show left off. In the early Middle Ages Pagan Germanic-language speakers like the Vikings are a dying breed. Many of their contemporaries wish they'd die faster.