Old Norse, the language of the Vikings, is a North Germanic language once spoken in Scandinavia, the Faroe Islands, Iceland, Greenland, and in parts of Russia, France and the British Isles. The modern language most closely related to Old Norse is Icelandic, the written form of which has changed little over the years, while the spoken form has undergone significant changes.
Between 800 and 1050 AD a division began to appear between East Norse, which developed into Swedish and Danish, and West Norse, which developed into Norwegian, Faroese, Icelandic and Norn, an extinct language once spoken in Shetland, Orkney, and northern parts of Scotland.
source
wikipedia.org,
omniglot.com &
ethnologue.com