eh, i think the roots of european behavior lie more in the way they consciously modelled themselves after the roman empire. the hypocrisy (rome never starts aggressive wars you see, they just need to defend the republic by going halfway across the world to burn everything down) , the slavery, the elite sucking up all the wealth, the sense of superiority over others (rome's version wasnt our modern racial hierarchy, but it was something in the same genre), etc...

the vikings were opportunistic pirates, sure, but mainly they were traders. and they didnt leave much of an institutional imprint.