Words of Old Norse origin have entered the English language, primarily from the colonisation of eastern and northern England between 865 and 954 CE (see e.g. Danelaw). Old Norse (abbreviated in dictionaries as ON) existed in its spoken and written form from the 8th century until its spread from Scandinavia to colonies as far west as Greenland and far east as Russia and the Baltic region (spoken by Swedish settlers).
The language diverged into West Norse (Norway, Faroe Islands, Iceland, and Greenland) and East Norse (Denmark and Sweden). With some minor regional variations in loan words, both West Norse and East Norse are essentially the same. The Vikings who raided and later settled in Great Britain came mainly from Norway and Denmark.