If it’s true the song is both from the invaders perspective, and those attempting to defend their home from an invader, and both sides are picking up their crossses and swords, it is highly unlikely the invaders were vikings in the sixth century. It is more likely the “invaders” were also from a Christian nation, and that would track for European history, given they were constantly at war with one another, in spite of sharing a faith.
If it’s true the song is both from the invaders perspective, and those attempting to defend their home from an invader, and both sides are picking up their crossses and swords, it is highly unlikely the invaders were vikings in the sixth century. It is more likely the “invaders” were also from a Christian nation, and that would track for European history, given they were constantly at war with one another, in spite of sharing a faith.