They say history is written by the victors, but what if the victims are the ones with the pens?

That is the bizarre circumstance surrounding the history of the Vikings, since the centuries-old myth that has come down to us about their brutal savagery originated with their victims—monks and priests—who had the monopoly on writing in that time.

As a result, the image we have today of the marauding Vikings is both wildly off the mark, and ignores the major contributions they made in shaping Europe during the Middle Ages. That demystification and deep dive into the world of one of history’s most iconic people is the subject of a new book, The Age of the Vikings by Anders Winroth. Not only are the Vikings completely misunderstood, he argues, but they may have saved Europe.

The Vikings weren’t picky about their raiding targets, but the short-term gains in booty and ransom achieved by attacking monasteries resulted in the Vikings being relegated to the “vicious barbarian” category of history. The monks in those monasteries were the only historians around at that time.

“Since [the Vikings] attacked those with a monopoly on writing, it is their deeds … that have gone down in history as infamous, irrational, and bloodthirsty,” writes Winroth.

A contemporary ruler like Charlemagne, he notes, is “today generally extolled as a founding father of Europe. France and Germany compete about who has the greatest right to claim him as their national founder.”

Charlemagne is the cultured hero of the age. The Vikings—not so much.

One of the reasons the Vikings are viewed so negatively is that their violence could seem wanton or irrational.

Part of that lies in the paucity of documentation of what the Vikings actually did during their raids. To many at the time—clerics in particular—attacking a monastery or church would have seemed irrational. Those who did document the raids, which were usually monks, had something to be gained by playing up the Vikings’ violence against religious figures, and they often resorted to broad, generic rhetoric about the “devastation” and “destruction” without specific detail.

Or, the documentation we are left with was written centuries after the events, often in poetry, often wrong. The horned helmets of the Vikings—they never existed. As for the other two famous images, the blood eagle and the berserker—those are the result of mistranslations.

The execution method of the blood eagle in which victims were sliced open along the spine, had their ribs snapped open so they looked like wings, the lungs pulled out, and salt poured in, maintains Winroth, is a mistranslation of Icelandic poet Sigvat Thordarson’s famous poem Knútsdrápa. The poem is about Ragnar Hair-Breeches’s sons slaying King Ella of Northumbria in revenge. The stanza in question has been translated as both “Ivar caused the eagle to cut the back of Ella” and “Ivar cut the eagle on the back of Ella.” However, argues Winroth, only the first makes literary and historical sense, as it fits in with the unique structure of Icelandic poetry as well as the tradition of describing a slaughter as providing carrion for birds. The second translation led to a 14th-century interpretation that still exists today of the Vikings enacting a particularly horrid form of retribution.

As for the berserkers, Winroth argues that they were also later creations of Icelandic poets who misunderstood the original poetic meaning in the Norse poem Haraldskvæði, which was talking about men in armor, not a mythic elite warrior.

“So thrilled by tales about Norwegian superheroes,” Winroth notes cheekily, “normally well-functioning critical faculties of historians and others have frequently been overwhelmed.”

More importantly, contends Winroth, the Vikings were acting completely rationally with their raids. These men weren’t addicted to violence—the treasure gained from the raids was used by chieftains in the complex and even poetic gift-giving system of the Viking halls. And, he argues, it was no different than Charlemagne.

For instance, he points out, Charlemagne treated Saxony like his own personal punching bag. On just one day in 782, “Charlemagne ordered no fewer than 4,500 Saxons decapitated” because they were oath-breakers. Meanwhile, because they attacked those who would control the written record, the Viking execution of 111 prisoners in 845 lives on in infamy. Winroth finds it ironic that Germany is so quick to extol Charlemagne, when “the Saxon ancestors of moderns Germans were among the longest-suffering of Charlemagne’s victims.”

According to Winroth, Charlemagne’s wars on his neighbors were not dissimilar from Viking raids in that their primary purpose, particularly the raids of Avar and Pavia, was booty for his currency-starved empire.

Which brings us to the utterly fascinating heart of the argument for why the Vikings are due for a makeover—their sophisticated and extensive trade network saved Europe.

“However disastrous and ruinous an individual Viking raid may have been for those attacked, the overall impact of Scandinavian endeavors was, unexpectedly, to stimulate the economy of Western Europe,” declares Winroth. Following the collapse of the Roman Empire, all of Europe faltered as trade and commerce dried up. While things had picked up by the height of the Viking era in the 9th and 10th centuries, two things were holding the region back. One was a negative balance of trade in Charlemagne’s kingdom and the region as a whole. This was largely due to currency being made of silver and gold, but the precious metals came from the East, Afghanistan in particular. The second factor was that in regions where currency was not used, the system in place was the barter system, which limits economic growth.

The Vikings solved these problems in two ways.

The first, and less significant one, is that by attacking the monasteries and churches, the Vikings tapped into the sole major untouched source of precious metals in Europe. Those riches did not disappear, as the Vikings were well integrated in the European trade network. They used it to buy anything from Frankish swords or mint them into coins for the kingdoms Scandinavian chieftains set up in England and Ireland.

“More important for the early medieval resurgence of commerce in western Europe was the central Asian silver that Scandinavian merchants brought to Europe,” argues Winroth. The trade network of the Vikings stretched from Greenland and Iceland in the west all the way to the caliphate and Bolghar in the east. The Vikings prodigious exports, mainly fur and slaves, “rectified for some time the lopsided trade balance between western Europe and the East.” The economic recovery in Europe, contends Winroth, “was during the Viking Age.”

The Vikings were not roving bands of berserkers ripping open people’s rib cages. They were undoubtedly violent, and slaughtered countless innocents. But, Winroth argues convincingly in this slightly dry book, that hardly made them unique in the 9th and 10th centuries. Furthermore, they left a huge impact on the region, through their establishment of Dublin, their legacy on the English language (ransack, skin, skirt, and doze to name a few words we take from them), their rule in England, their trade with the Caliphate, and the (disputed) extent to which they made up the Rus people.

But clearly, the moral of the story is, just don’t mess with monks.