The Viking-controlled region in eastern and northern England was called the Danelaw.
The Danelaw was the area where Danish law and Scandinavian political influence predominated after Viking armies seized territory in Anglo-Saxon England. Its boundaries were shaped by agreements between Viking rulers and English kings, especially the treaty between Alfred the Great of Wessex and Guthrum after Alfred’s victory at Edington in 878.
The term refers both to a territory and to a legal-cultural system. Scandinavian settlers influenced place-names, personal names, farming patterns, and vocabulary. Hundreds of English place-names ending in “-by,” meaning farm or settlement, reflect Old Norse influence. The Danelaw was not a single unified Viking kingdom throughout its history; control shifted among rulers and was gradually absorbed by the English monarchy.
The region broadly covered much of the Midlands and northern England, including important towns such as York. It is therefore different from Wessex, the Anglo-Saxon kingdom that resisted Viking conquest, and from Northumbria, an older English kingdom that partly fell under Norse rule.