This is a somewhat brief overview of a four century long Viking period, starting with groups that were like tribal mauraders gathering loot, and progressing through periods of colonization and eventually established national governments. It was not that far back that Sweden was a msjor power in Europe, controlling an area much larger than present day Sweden. The Danes briefly controlled England and Ireland before being driven out. Rollo established a much more enduring kingdom in Normandy. Many of us alive today are descended from various intermarriages.
The author tries to separate fact from myth, a major endeavor. Storytellers writing sagas tended to use a great deal of literary license. There are undoubtedly true facts behind stories like Beowulf, but it requires some interpretation to separate the facts from fiction. One can wonder about the legendary Sigurd, slayer of the dragon Favne. Much of what we know comes from the so-called Icelandic Sagas.
The author does provide a good general picture of the period. Three was established trade in commodities ranging from fur and amnber to slaves (yes, original slaves were white). There was an established social order of freemen, freed slaves, and slaves. The author mentions the practice of weregild, i.e., the payment of money to the family of someone whom you killed - a practice that still exists between tribes in Afghanistan.
Overall, it is a good book to read if you have an interest in the society of the Viking period.