If what Oppenheimer states is true, then the written histories on both the English and British/Welsh sides describing mass slaughter in the 5th and 6th Centuries are inaccurate. Additionally, I have read other information that indicates a great deal of genetic difference between the English and the Welsh. The general observation in Britain also indicates a greater degree of fair hair and eyes in the eastern parts, with darker hair and eyes more common in the west, especially Wales and Cornwall. This would seem to agree with the concept that a great amount of German and Scandinavian ancestry can be found in eastern England and Scotland, while the older inhabitants, perhaps with ties to northern Spain and western France, are better represented in western Britain.
Correct.
English And Welsh Are Races Apart
I highly recommend Oppenheimer's book.
Also, Bryan Sykes latest: Saxons, Vikings, and Celts: The Genetic Roots of Britain and Ireland is a goodbook.
If you choose between the two, choose Oppenheimer's.
"Everything you know about British and Irish ancestry is wrong. Our ancestors were Basques, not Celts. The Celts were not wiped out by the Anglo-Saxons, in fact neither had much impact on the genetic stock of these islands".(Stephen Oppenheimer)
Even those that occurred before that time usually highly little more than the killing of other nobles with the broad masses being fairly immune from battlefield deaths. That comes later after massproduction of steel becomes possible, and increases at a tremendous pace with the arrival of firearms. You can imagine what we can do with nukes.