A small population from Scndinavia was vey successful for a few hundred years.
They invaded then merged in the British Isles. They conquered then merged into northern France. William the Conqueror who in 1066 took over England was a Viking descendant.
They went far into Russia and Asia, started the Kievan Rus culture, which is the basis for Russia that followed.
http://en.wikipedia.org/wiki/Kievan_Rus%27
They sailed into the Mediterranean, and made an empire from southern Italy to Turkey.
http://en.wikipedia.org/wiki/Norman_conquest_of_southern_Italy
They sailed to north America. You all know that story.
Few cultures can boast the influence achieved by such a small population. Today the Scandinavian countries’ population is less than 20 million. At home in the face of a hostile climate, they prosper as few others do.
The Scandinavians had a big population explosion as a consequence of the Medieval warming; Viking-era farmsteads are found (as ruins) both farther north and at higher altitudes than are viable today.
They controlled a long route based on rivers and portages, and worked for the Byzantine emperors as the Varangian Guard, becoming both wealthy and powerful. That went on for a couple centuries.
Hardrada was working for the Byzantine general tasked with pushing the Saracens out of Sicily; the Saracens broke up pottery behind them to prevent a cavalry charge, so Hardrada had his cavalry wrap the horse’s hooves with palm fronds cut from the nearby trees, and charged them anyway.
The later Norman kingdom in Sicily didn’t last long, only two generations.