Forget the funeral boats burning at sea and tales of the most bloodthirsty warriors in history. In fact, you can forget pretty much everything you think you know about the Vikings—it’s all wrong. Many of the legends associated with the Norse raiders were invented by their victims, whose written accounts dominated the narrative long after the Viking Age.

In truth, the Vikings’ most remarkable achievement was setting up an extraordinary intercontinental trade network that surpassed even the great Roman trade routes. That is not to suggest these Norse adventurers were anything less than fearsome, indeed the first phase of globalization arrived in North America powered by the Vikings’ innovative and gruesome slave industry. Their unparalleled reach across the globe is the subject of a new exhibition at the British Museum in London, which goes beyond the legend of the Scandinavian explorers.

One brutal exhibit features a recently discovered mass grave in Dorset, southern England. Around 50 men, whose bones can be traced back to Scandinavia, were rounded up and beheaded at some point in the 11th Century. It’s hardly the kind of scene you find in the terrifying, florid descriptions of unbeatable Norse raiders written by monks and churchmen at the time.

The discovery, made near Weymouth in 2009, is thought to have contained remains of the entire crew of a medium-sized warship who were captured, stripped and executed. According to an account in The Anglo-Saxon Chronicle, written in the 9th century, that failed Viking raid was hardly a one-off. In 896, a group of six Viking ships were said to have been fought off by locals leaving only a few survivors who were “very much wounded.”

These battlefield set-backs were extremely common said Gareth Williams, curator of “Vikings: Life and Legend.” “When it came to actual battle the Vikings were no more successful than their enemies,” he said. “Where they could, they tended to avoid combat. If you can get what you want without having to fight for it that enhances your profits, and enhances the chances of you living long enough to enjoy the profits.”

So where did the Vikings’ traditional rape and pillage reputation come from? Horrifying tales of their brutality have been around for centuries. The death of King Ella is a good example; he was supposedly executed in York by having his ribs cut along the spine and splayed out to resemble wings, in a technique known as the Blood Eagle.

It seems this was a rare era in which history was not written by the victors; mostly because the victors couldn’t write. It was left to monks and Christian churchmen to craft the only contemporary accounts of many of the Vikings’ raids, and Vikings did attack churches, which held no sacred mystique for them. They were simply seen as easy, wealthy targets, confounding local conventions of the time.

“These accounts are dressed up in the language of religious polemic,” Williams said. “Many [of the stories] were borrowed from earlier accounts—from classical antiquity. The violent reputation and particularly the reputation for atrocities was created then, but the Vikings were probably no worse than anyone else.”

There was a revisionist phase in the late-1970s when historians began to suggest that these accounts couldn’t be trusted at all—and that perhaps the Vikings were just successful traders. The latest research suggests a middle-ground, and it's worth looking at what they were trading.

“There’s not much distinction between the Viking as the violent raider and the idea of the Vikings as the peaceful trader if you’re talking about the slave trade,” Williams told the Daily Beast. “We've got accounts in Irish, Anglo-Saxon and Frankish sources of fleets of Vikings descending on an area and carrying off hundreds of slaves at a time. It's not far removed from what was happening on the West Coast of Africa in the 18th century. There's a bit of a tendency to see that slave trade as unprecedented—it's acquired particular overtones because of the color, but in terms of what was happening, the slave trade in the Viking era was fundamentally very similar.”

The remains of the longest Viking warship ever discovered stands at the center of the British Museum’s exhibition. It’s surrounded by a 120-foot recreation of the original vessel, which was found in the late-1990s. It was these powerful, flat-bottomed boats that allowed the Vikings to set up the unprecedented network through which they traded furs, falcons, walrus ivory and slaves for spices, silk, silver and jewelry.

The design of the boats revolutionized trade and raiding: Their power allowed the Vikings to cross major seas in relatively small vessels, while the flat bottoms allowed them to dock on beaches or travel inland along rivers. One famous maritime Viking legend, however, is supported by absolutely no evidence.

The only contemporary record of a funeral pyre in a boat pushed out to sea comes in a description of the burial of Baldr, a Norse god and son of Odin. “Certainly not an eyewitness account!” said Williams. For obvious reasons, there is also no archaeological evidence of sea burials.

“Boat burning on land certainly did take place though,” said Williams. “Ibn Fadlan, an Arab traveler, described a funeral on the banks of the river Volga by the Rus—the Vikings who give their name to Russia—with a sacrificed female slave who has ritualized sex with most of his followers before being killed and put into the boat with him. She is killed by a priestess they call the Angel of Death.”

In addition to Russia, the Vikings were also instrumental in the foundation of modern Ukraine. Thomas Williams, author of The Tale of King Harald: the Last Viking Adventure, said it was the legacy of the Vikings that helped define the battle between the West and the East that continues to this day. “The origins of Kiev and Rus were really established by people who identified as Vikings,” he said.

Vladimir the Great of Kiev, who described himself as a descendant of the Vikings, decided to adopt Christianity in the 10th Century. He chose the Orthodox church rather than Western Christianity. “It’s an entirely different identity for those parts of Europe with a Viking heritage as opposed to western Europe—so you can trace some of those tensions back to quite an early point in the past,” he said.