It strikes me after reading about the Anglo-Saxon settlement of England that the origins of the Anglo-Saxons and their ethnic background and even the means by which they came to England is very similar to that of the Vikings.

Both groups originate in Scandinavia and Norther Germany, both groups speak related languages, and both groups came to England as naval invaders and eventually colonists.

And yet both popular culture and history seem to suggest that the Vikings (or Danes) and the Anglo-Saxons were extremely different groups of people, that the Vikings terrified the Anglo-Saxons, and that when Vikings settled the did so in their own state (the Danelaw) with significantly distinct differences to the Anglo-Saxon kingdom of England.

Did the Anglo-Saxons not realize that the Vikings had similar geographical and ethnic origins to themselves? How is it that people with such similar origins and related language and ethnicity could come to be so alien from each other in a matter of a few hundred years (from the beginning of the Anglo-Saxon settlement of England c. 500 and the beginning of the Viking raids and invasions c. 800).

Or is this just an artifact of pop culture and obsolete historiography and the reality was more like a protracted struggle for land and power between a spectrum of similar and related peoples?