By the way, Viking is a historian term, as far as I know. It was not used in the period or at least not as it is used now. Correct me if I'm wrong.

Also, surely you wouldn't call (now or then) Mediterranean-born pirates Vikings.

Not an expert on the matter, just a Swede but it was used about pirates in general from any country in medieval Swedish and I think Icelandic. And it was used in period English and Frisian sources too, though there it might not have been about all pirates. It is also on a couple of rune stones but on the one I know of it is used to refer to the activity of going raiding.