They didn't reach Baghdad as pirates, one would assume.
The Vikings traded, as well as raiding. And their were more than one kind of Viking, as they're called now.
Perhaps they did introduce elements of their age-old legal traditions to parts of the Islamic world, but it's hard to see what they could have been.
The Muslims wrote down all their sources and translations, something in which western history is strangely lacking.
But I will case Muslim historians for Viking input.
Btw, Vikings were traders? I was under the impression they were an overpopulated gang that was forced to plunder for survival and made a good job of it for several centuries.
Damn, Hagar the Horrible isn't real?