Original: Near the end of Charlemagne's reign (and throughout the reigns of his sons and grandsons), a string of Norse raids began, culminating in a gradual Scandinavian conquest and settlement of the region now known as Normandy.
Simplified: Near the end of Charlemagne's reign and throughout the reigns of his sons and grandsons, a string of Viking raids began, leading to a Scandinavian conquest and settlement of the region now known as Normandy.