Final answer:
The Viking raiding period in Norway began in the eighth century and gradually declined as Scandinavian kings asserted control and the conversion to Christianity became widespread.
Step-by-step explanation:
In the eighth century, the Norse, known as Vikings, began raiding European territories. They attacked Christian monasteries and settlements, primarily targeting churches and monasteries for their loot. However, as powerful states emerged in Scandinavia itself and the kings began to assert control, Viking raids began to decline. The conversion to Christianity by the Scandinavians also played a role in ending the raiding period.