The world it came from
The Valknut belongs to the century in which Scandinavian sea-power turned outward. Gotland, where most examples survive, was not a kingdom but a league of farm-holders grown rich on Baltic and eastern river trade; its picture stones were raised at farm boundaries and along roads by families with silver enough to hire a carver. The sign therefore appears in a society where a man's death abroad — drowned, hanged, killed in a raid — was common enough to need a public monument, and where that monument doubled as a claim to land and lineage.