Were the Vikings really that violent?

Vikings are often depicted as brutish, bloodthirsty warriors with battle axes and horned helmets. In popular culture, Vikings are shown raiding, pillaging and murdering anyone in their path and performing grisly executions, like the infamous "blood eagle."

But is the Vikings' ruthless reputation warranted?

"The question isn't, 'Were Vikings violent?'" said Daniel Melleno, an associate professor of medieval and pre-modern history at the University of Denver. "They were absolutely violent. It's just a question of, are they doing something that is out of the norm?"

The Viking Age lasted from about A.D. 793 to 1066, coinciding with Europe's Middle Ages — an already-violent time, Melleno said. In this era, wars, slavery and raids were commonplace, and the Vikings were no exception. With fast and mobile longships, the Vikings were experts at launching surprise attacks from the sea.

Related: Why didn't the Vikings colonize North America?

One of the Vikings' first raids was on a wealthy monastery in the British island of Lindisfarne in A.D. 793. The Vikings frequently attacked monasteries, which were poorly guarded and filled with riches. Because the Vikings were initially pagan and their victims were Christian, their attacks were described as particularly abhorrent and ungodly.

"These are Christians writing, and they talk about these 'heathens' or 'pagans' attacking," Caitlin Ellis, an associate professor of medieval history at the University of Oslo, told Live Science. "Sometimes they even say it's a punishment from God that their own people have sinned or not been good enough."

Unlike their southern neighbors, the Vikings were largely preliterate; they left only a few runes of their activities. Some of the only written evidence of their actions comes directly from their victims or from sagas written hundreds of years later by the Vikings' descendants. Although the Vikings were also merchants, farmers and fishers, their victims were, justifiably, more focused on the violence committed against them, Melleno said. Over the years, stories of Viking brutality were also likely embellished.

"Some of the sources that are most negative in the way they describe the Vikings as being particularly ferocious or barbaric are actually from a bit later," Ellis said, "from the 12th century, so a few hundred years after the raiding had begun. So maybe there's a bit more exaggeration with time that plays into the image that we still have today."

In addition, discrepancies in some sources' writings cast doubt on their legitimacy, Melleno said. For example, an account from the chronicler Prudentius in A.D. 834 describes the Vikings destroying everything in the town of Dorestad, in what is now the Netherlands. But the next year, the village was still standing for the Vikings to "lay waste" to it, Prudentius wrote. The Vikings returned in 836 to destroy the town again, and then again in 837, he reported.

"If we look at the archaeological record, one of the things we don't often see is mass graves or burn layers — the signs of that destruction that we would expect to see if we read the sources and took them at face value," Melleno told Live Science.

The Vikings were not the only group raiding and conquering towns in medieval Europe. Muslim raiders called "Saracens" frequently attacked parts of what are now France, Switzerland and Italy. The Magyars, a group from Hungary, attacked what's now Bavaria. And Charlemagne, king of the Franks, waged a decades-long war against the Saxons that resulted in mass killings, hostage taking and pillaging in what's now Germany.

"What's the difference between Viking raiding and Frankish wars of conquest? Really, not that much," Melleno said, adding that it comes down to state violence versus stateless people committing acts of violence. It's likely that because the Vikings weren't part of a formal kingdom, their victims saw them as more unpredictable and barbaric.

"The Vikings come off as bad because they're not a state waging war," he explained. "The Vikings don't have a country, and they barely have a king … so it's just a bunch of pirates."