Most likely they raided Spain when it was Al-Andalus.

Tho vikings did have a phase where they served as bodyguards in Byzantine empire. They definetely bought stuff from a muslim merchant.

Second point is more interesting because not one history teacher I had went over how focused mediveal muslims were when topic came to merchants. Last prophet in Islam was a regular merchant until he was past 40.

You can imagine trading becoming a core part of religious culture over time. To this day you can negotiate prices when buying anything from any religious muslim by saying "The Prophet used to bargain."