For a summary of the damage the Viking raids inflicted in Frankia (roughly consider that as France or western Europe) from around 830 A.D. through around 890 A.D., consider the analysis by Neil Price in Children of Ash and Elm / A history of the Vikings.

He points out in about a century the Vikings went from perhaps a dozen men on the beach at Lindisfarne to thousands of Vikings on hundreds of ships besieging Paris for a year.

The starting caveat in his analysis is that we have to assume the comments in the various official chronicles are correct. A large assumption, but we can make no other.

How much silver did the Vikings take away?

Those accounts suggest the Vikings were paid somewhere around 30,000 pounds of silver. That would be equal to about 7 million silver pennies. (That would be the expected ratio of 240 pennies to a pound.)

For context, the output of the Frankish mint during that time was around 50 million coins.

That means the Vikings walked away with silver equal to about 14% of the total mint production of the Frankish Empire over the course of about 60 years.

He points out that in addition the Vikings would have walked away with plenty of grain, wine, horses, livestock, and other stuff from towns and villages they agreed not to pillage and loot. They would have taken the same items from towns and villages who could not come up with a sufficient bribe.

Author mentions that from 830 through 890 there were 120 settlements that are specifically listed as having been looted and destroyed.

Author mentions the obvious – it is completely impossible to tally the staggering human cost in terms of death during raids, suffering, starvation after villages were looted with barns stripped bare, and widespread abduction into slavery.

Update:  Not that it is any consolation to anyone, but the same swathes of devastation were caused by Charlemagne, English kings, attacking Muslim armies, Magyars, and everyone else who went on the warpath in the Middle Ages.