The Vikings' impact in England was considerable. Their invasions effectively eliminated the kingdoms of East Anglia, Mercia and Northumbria, leaving Wessex as the only Anglo-Saxon Kingdom. When Wessex conquered the Danelaw in the 10th century, the English were for the first time united in a single kingdom. Thus, England owes its existence as a unified kingdom indirectly to the Vikings. The extensive Danish settlements in Eastern England had a long-lasting influence on local legal customs, and a wider impact on the English language through hundreds of Scandinavian loan words, including ones such as 'sky', 'skin', 'get', 'egg' and 'sister'. The Viking attacks on monasteries certainly caused a great deal of cultural damage, but English monasticism made a strong recovery in the 10th century. Viking roads must also have caused much short-term economic hardship for their victims through losses of livestock, seed corn and manpower. In the longer term the Vikings may have promoted urbanization, both directly through trade at centres like York and Lincoln, and indirectly by prompting the Anglo-Saxons to found fortified settlements called burhs.
The Scandinavian settlers in England were assimilated into the native population within a few generations by intermarriage and conversion to Christianity. Archaeological evidence of the Scandinavian settlement is limited. There are a few pagan burials and many works of sculpture showing the influence of Scandinavian art styles, but from apart from at York no Scandinavian settlements have been identified with any certainty. Evacuations of Viking Age farmsteads at Ribblehead in North Yorkshire, Goltho in Lincolnshire, Bryants Gill in Cumbria and Simy Folds in County Durham, each one in an area settled by Scandinavians, have all failed to produce distinctively Viking artefacts. The most important source of evidence for Scandinavian settlement comes from place-names. In the old Danelaw counties of eastern England, Danish influence in place-names ending in -by, as in Thurkleby (Thurkil's farmstead), and -thorpe, as in Kettlethorpe (Ketil's outlying farm). Hybrid names incorporating a Danish personal name and the English element -tun, as in Grimston (Grim's village) are also common in the Danelaw. Norse place-names are common in north-west England, especially in Cumbria. Typical Norse place-name elements include -thveit, as in Brackenthwaite (bracken clearing), soetr, as in Gunnerside (Gunnar's shieling) and in fjall, as in Scafell (crag hill).
Notes from Encyclopaedia of the Viking Age by John Haywood. Thames & Hudson 2000. pp65-66.