Recent archaeological finds have shed new light on the "Viking Age", depicting a stable society based on land-owning and agriculture, with a hierarchy ranging from wealthy aristocrats to the "unfree" (slaves), and a quasi-democratic system focused on the local parliament, or "Thing". Attitudes towards women were enlightened - at least compared with the Christian Middle Ages. Women ruled the household and farm, their power symbolised by the decorative bronze keys they wore on their belts. They were often buried along with their keys. Women could also get divorced.
So, is there any substance in the traditional image of the bloodthirsty warrior rampaging across foreign lands, or were the Vikings refined, sensitive creatures who have been victims of a bad press?
Some of those who left their farms to "go on a Viking" (meaning an adventure or activity - that was how the word was used in those days, not as a descriptive term) did take part in violent raids. These included a notorious attack in 793 on a monastery on Lindisfarne Island, in Northumbria, England, widely considered to signal the start of the Viking Age. However, Scandinavians also travelled abroad to engage in commerce, setting up numerous trading posts and towns. And, according to Gapp, they were probably no more warlike than, say, the Anglo-Saxons or the Franks of that era.
"What distinguished them was their shipbuilding technology, which meant they could travel vast distances really quickly, make surprise attacks and escape," he says. "That was the key to their success in both trading and raiding: these amazingly long ships that they built."
The exhibition, put together by the Swedish History Museum, features a reconstruction of a longship found in a grave near Stockholm, in 1933. Such ships could accommodate 50 to 100 rowers. The Vikings were able to navigate without instruments, relying on their knowledge of the winds, tides and weather, and were also expert ship-builders, handing down their skills through the generations.
They went overseas, too, in order to colonise, using violence to subdue resisting populations across Europe, North America and North Africa.
In England, King Alfred was forced to hand over large chunks of the central and eastern parts of the country. Women sometimes went along on such trips; swords found in their graves indicate they may have joined their men on the battlefield.
One of the surprises of the exhibition is the ornate, colourful jewellery on display, some of it created by local craftsmen, some acquired through trade, particularly in the Near East and Russia. The Vikings worked with silver, gold, amber and turquoise to make pendants, brooches, bracelets and belt buckles. They also produced highly decorative swords and knives, and musical instruments such as jaw harps and bone flutes.
Also unexpected is a collection of nail scissors, combs, tweezers, mirrors and ear scoops. "We think of the Vikings as quite uncivilised and unkempt, but they were much into personal grooming," says Gapp. The wealthy wore finely embroidered silk and linen clothes and, far from greedily snatching food and eating it with their hands, Vikings also had good table manners, using cutlery made of bone, horn or wood.
For many, though, it was a harsh life. As few as half of children reached the age of 10, and the average adult life expectancy was 30. Life was toughest for slaves, most of whom were captured in battle in the Near East, and who were put to labour on the farms.
Gapp - who wrote a PhD on historical re-enactments - attributes our long-standing fascination with Vikings to the work of early archaeologists, and the popularisation of the warrior stereotype through the Ring Cycle and Hollywood.
Over the years, the Viking Age and its legends have been exploited by, among others, the Nazis, who - during the German occupation of Norway and Denmark in World War II - promoted the myth of the strong, Aryan Viking to recruit Norwegian, Danish and Swedish soldiers.
As for the horned helmet, it may have been worn for ceremonial purposes, but in battle it would have presented an easy target for an enemy, who could have hooked the horns and broken the wearer's neck. "It would have defeated the purpose of the conical helmet, which was to deflect blows," says Gapp.
