Viking Myths & Misconceptions
http://norse-mythology.net/myths-and-misconceptions-about-the-vikings/
#4 They were a nation
"The Vikings were not one nation but many small different groups of people lead by their own chieftain. Neither Norway, Denmark or Sweden was even a kingdom before the end of the Viking age. Some of these small kingdoms did, however, work together when they went on big raids in foreign lands."