The conquest and settlement of lands in eastern England by Scandinavians represents an extreme migratory episode. The cultural interaction involved one group forcing themselves upon another from a position of military and political power. Despite this seemingly dominant position, by 900 CE the immigrants appear to have largely adopted the culture of the Anglo-Saxons whom they had recently defeated. Informed by migration theory, this work proposes that a major factor in this assimilation was the emigration point of the Scandinavians and the cultural experiences which they brought with them. Although some of the Scandinavians may have emigrated directly from Scandinavia, most of the first generation of settlers apparently commenced their journey in either Ireland or northern Francia. Consequently, it is the culture of Scandinavians in these regions that needs to be assessed in searching for the cultural impact of Scandinavians upon eastern England. This may help to explain how the immigrants adapted to aspects of Anglo-Saxon culture, such as the issuing of coinage and at least public displays of Christianity, relatively quickly. The geographic origins of the Scandinavians also explain some of the innovations introduced by the migrants, including the use of client kings and the creation of ‘buffer’ states.