From The Viking Word Hoard

At the beginning of the 9th century, the growing population of the three great branches of the Scandinavian race who peopled the countries abutting the Baltic - the Norsemen or Northmen, the Swedes, and the Danes - began a great outward movement which was caused both by political changes and their enterprising nature. Thus the 9th century came to be known as the Age of the Vikings, Vikinga-Old. The Danish emigration directed its course to the north-east of England. The second migration was Norse, whose settlers gradually peopled the coasts of Ireland, northern Scotland, and the Isle of Man. They left a lasting linguistic heritage. This book is a glossary of words in the various languages of Britain and Ireland which owe their origin to the intrepid raiders and merchants of Scandinavia.