Rollo was a Viking who, as Count of Rouen, became the first ruler of Normandy, a region in today's northern France. He emerged as a leading warrior figure among the Norsemen who had secured a permanent foothold on Frankish soil in the valley of the lower Seine after the Siege of Chartres in 911. Charles the Simple, king of West Francia, granted them lands between the mouth of the Seine and what is now Rouen in exchange for Rollo agreeing to end his brigandage, swearing allegiance to him, religious conversion and a pledge to defend the Seine's estuary from other Viking raiders.

Normandy is a geographical and cultural region in northwestern Europe, roughly coextensive with the historical Duchy of Normandy.