They were merchants ~ with a lengthy history of engaging in human slavery.
Part of the problem of dealing with the Viking raiders is their profound separation of society into "man's world" and "woman's world", with all of the women servants to the men, and within "man's world", a leadership elite that got the first share of the booty, and the rest of the men considered servants.
The status of women in Viking society was AT THE BOTTOM. These guys would sell their own daughters, much as they'd sell a cow, or a pig.
If you read through the Icelandic Sagas you will find that most of this crowd of "outcasts" consisted of a handful of Swedish/Norwegian criminals, their sailors, and a flock of Irish slaves!
THe same stuff went on in Russia.
There's a classic book with the simple title "History of the Vikings" out there ~ has about 500 pages ~ you can read it in a weekend. BTW, if you read Shakespeare's "MacBeth", you would have encountered "Lady MacBeth". This co-foundress of the Alexander clan in the Highlands was the daughter of a Viking King! If you ever wondered how it was she became so nasty, you read that "History of the Vikings" and you'll understand her more than you ever imagined.
On the good side, the Vikings founded the first cities and towns in Ireland, and pretty much organized, or forced the organization of the wild Slavic tribes riding the steppes in Russia!
Definitely some interesting folks.
Gotcha.. incidentally, there happen to be more than one books by the same title (a history of the vikings).. which one do you recommend ?