>>12146499Thralls that were capable and willing to be fighters, became fighters, free from slavery by the merit of their ability. Some viking graves unearthed had alot of varying "diversity" as it was, imply that the term Viking often had more in common with a job-description than a tribe/culture/people from a given place.
Could also be that viking culture influenced various other factions at the time, and that the graves in question were influenced enough to confuse archaeologists?
Can't know for sure.