Drawing from recent archaeological and linguistic evidence, as well as more traditional literary and narrative sources, the author distinguishes between the initial phase of migrations in the ninth and tenth centuries, and the secondary period of settlement up to c. 1100 AD. He emphasizes, too, the differences in nature and intensity of the Viking impact on the societies that were slowly developing into the historic kingdoms of England and Scotland, and the more complex political structures of Wales and Ireland. Throughout the book, the effects of the Scandinavian invasions on Britain are set within the wider European context.