From the ninth through the eleventh centuries, the fearsome Germanic Scandinavian seafarers known as the Vikings, or Norse, raided and settled many regions of Northern Europe. Denmark and Scandinavia were well outside the borders of the Roman Empire, and by the end of the eighth century the region contained many small tribal kingdoms, where farming and fishing accounted for most of the economy. However, a growing Norse population found that its fertile land was in limited supply.
Why did the Norse probably develop their reputation as warriors and plunderers?
The fact that their fertile land was limited was probably the reason for the Norse movement to find new homes across the seas. Wherever they were not welcome, they saw little practical choice but to seize land by force.