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The Vikings’ ancestors may have raided the North Sea coasts as early as the 3rd century

The Roman Empire's naval bases probably gave them the idea for similar structures in southern and western Norway.

Miniature Viking longboat and figures near wooden huts on a grassy model landscape

This is what it may have looked like when ‘Vikings’, long before the actual Viking Age, pulled one of their ships out of the boathouse at Karmøy, on the western coast of Norway. In the background, a large boathouse under construction 1,700 years ago. Model made by Rezas Ghoumi.

(Photo: Terje Tveit / Museum of Archaeology in Stavanger)

Bård Amundsen Bård Amundsen Bård Amundsen JOURNALIST

Published 21 February 2026 - 00:01

“Perhaps there is reason to ask whether the Viking Age actually began as early as the 3rd century,” archaeologist Frans-Arne Stylegar tells Science Norway.

Many hundreds of years before the Viking Age, he sees clear evidence of something like Vikings along the coast of Norway.

In recent years, Stylegar has worked to map their bases.

Somewhere in southern Norway, he believes there's something quite special.

Have found many naval bases

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Archaeologists have now found traces of many large boathouses – ship houses – along the Norwegian coast facing the North Sea and Skagerrak.

These have been dated to between the years 180 and 540.

Most of these years fall within the Roman era. This was a time when people in today's Norway most likely were much more involved with the Roman Empire than has previously been thought.

The boathouses are often over 20 metres long. Some are much larger. Many are built in clusters.

Excavated shoreline site with rows of pegs sticking out of the ground — The pegs mark the post holes of two large boathouses on Rennesøy, north of Stavanger.

“These buildings have long been interpreted in the context of local military power,” Stylegar says.

In other words, they were associated with conflicts between local groups in western and southern Norway.

“I believe the boathouses must be seen in a broader historical context,” the archaeologist says.

What would people need such large ships for?

Stylegar has long been fascinated by Norwegian boathouses from the Iron Age. These large structures are much older than the Viking Age.

What would people in Norway in the 3rd, 4th, and 5th centuries need so many large ships for?

Why did they need so many people on their ships, as the up to 1,800-year-old boathouse ruins in southern and western Norway clearly suggest?

“I think the answer lies just as much in overseas raids as in more local conflicts between various chieftains and warlords here at home,” says Stylegar.

They had Roman military expertise

In the Norwegian finds, the archaeologist sees evidence of Roman military expertise linked to seafaring.

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He also sees signs of Roman-inspired naval organisation in Norway in the form of naval bases along the coast.

Archaeologist Dagfinn Skre recently told Science Norway about his theory of how people from Norway went as mercenaries to the Roman Empire and how this completely changed society back home in Norway from around the year 180.

Archaeologist Frans-Arne Stylegar's theory is that many people from the coastal areas of today's Norway may have worked as mercenaries in the Roman navy at about the same time.

They would have gained a lot of naval knowledge at the Roman Empire's naval bases in England and France.

They brought this knowledge back home with them.

Map showing boathouse finds along Norway’s coast. — The map shows places along the coast of Vestlandet, Sørlandet and Trøndelag County where large boathouses from the Norwegian Roman period have been found – possible naval bases. The densest findings are in Rogaland County.

The origins of the Viking Age

The Vikings and the Viking Age did not arise in a vacuum.

Historians and archaeologists have focused on the possibility that before the Vikings, there were people called sea kings along the Norwegian coast. These sækonungr are mentioned in sagas from the Middle Ages.

They have been seen as a precursor to the Viking Age and the Vikings' warfare at sea.

But even earlier – all the way back to Norwegian Roman times – large boathouses were built in clusters along the coast of western and southern Norway.

Grassy hollow of a boathouse site with a forest in the background above a sketch reconstruction of the long wooden building. — At Stend, just south of Bergen, there was a boathouse that was a whole 32 metres long. When it was excavated a little over 50 years ago, the remains of two hearths were found inside the building. More than 800 such boathouse foundations have been recorded in Norway. Most date from between the years 200 and 800. The largest may have been 40 metres long.

Latin texts tell the story

In a yet-to-be-published scientific article, Frans-Arne Stylegar connects what he has found with what Roman texts written in Latin can tell us. These report on piracy in the North Sea and the English Channel in the 4th and 5th centuries.

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“In the Roman texts, it's often said that ‘Saxons’ carried out this pirate activity,” he says.

Both Stylegar and other archaeologists and historians believe that saxons is a general term for sea warriors. The name probably comes from the weapon sax – the large knife or short sword that was common among Germanic warriors.

And it's quite possible that these Saxon pirates came from the coast of Norway.

Saxony is also the name of a geographical area in northern Germany. But this name only emerged later, in the early European Middle Ages.

A Norwegian warship in Denmark?

Archaeologists have not found any preserved ships from that long ago in Norway.

But outside the city of Sønderborg, in the far south of Jutland in Denmark, a ship built around the year 320 was found around 1860 – in a bog called Nydam Mose.

The Nydam Ship is extremely well preserved.

The ship was sunk in what was once a small lake. It was likely a ritual sacrifice, after the ship had been taken as war booty. The lake later became a bog.

Preserved Nydam oak warship hull on display inside a museum gallery — The Nydam Ship was built for speed and military activity, not for trade. Were these the kind of ships found in the large boathouses in western and southern Norway? The oak ship had room for around 45 people, 36 of whom were rowers.

A common interpretation is that the Nydam Ship belonged to a foreign military force that was defeated by the local population.

Were these pirates from Norway?

We don't know. What Stylegar suggests is that ships similar to the Nydam Ship were also in use in Norway and were stationed at naval bases along the coasts of western and southern Norway.

Something very special in southern Norway

Lindesnes is Norway's southernmost point. The Lindesnes peninsula has only a narrow link to the mainland.

Motorboat with passengers cruising through a canal beside paths and houses. — The Spangereid Canal was opened as recently as 2007 and was built for pleasure boats and smaller commercial vessels.

This is where Frans-Arne Stylegar believes he has found something very special.

The Spangereid Canal now runs through that narrow link to the mainland. It makes it possible to avoid the harsh coastal areas in southern Norway – where the Skagerrak becomes the North Sea.

But a concentration of large boathouses from Roman times has also been found here at Spangereid.

Stylegar believes that there may also be evidence of a very old canal here. If so, it would have been a clever construction nearly 2,000 years ago.

The canal connected the harbour and the boathouses with the fjord system north of the narrow isthmus in southern Norway. The archaeologist thinks it had a military function: the canal provides two exits for the harbour. If there was a surprise attack on the naval base in Spangereid, the pirates who were based here could retreat and get to safety inside the fjords on the far side.

Stylegar thus interprets the canal as a military facility. The construction has clear parallels to Roman engineering and Roman naval harbours.

An ancient canal

Stylegar bases the theory that there was an ancient canal here on the fact that there is an elongated, and probably man-made, depression in the terrain, running across the isthmus at Spangereid.

Local people have long interpreted this as evidence of a very old canal.

Man sits on a chair indoors wearing a black graphic T-shirt. — Frans-Arne Stylegar has studied the many very old boathouse sites in Norway.

A 2001 archaeological survey showed that the depression could not be natural. It must be the remains of something that had been dug out.

But otherwise, there's no definite concrete evidence of a canal. Was it perhaps more of an excavated trench along which ships could quickly be hauled?

Pollen analyses show that the excavation work must have taken place more than a thousand years ago.

A thalassocracy in Norway

The boathouses from the Roman era that have been found in clusters in many places along the Norwegian coast are too large to have been built for the fishing boats of the time.

Much is similar to how the Romans designed their boathouses, according to Stylegar. The canal in southern Norway may point towards advanced military planning, inspired by similar canals in the Roman Empire.

According to Stylegar, these 'Vikings' long before the Viking Age in western and southern Norway show strong sea power without control over fixed kingdoms on land. Archaeologists and historians call this kind of power structure thalassocracies. There were several of them around the Mediterranean.

A long ship’s curved wooden prow displayed in a museum gallery with other boat exhibits. — The Nydam Ship was built between 310 and 320. It was sunk in a lake, which has now become a bog, sometime between 340 and 350. The ship is clinker-built, like Viking ships and newer wooden vessels. This means that the planks in the hull overlap each other and are fastened together. The Nydam Ship has a keel of oak that is more than 14 metres long. The last thing that is suggestive of a Viking ship are the curved prows at each end. The ship weighs three tonnes and had room for 36 rowers. The oars were probably 3.5 metres long. At the back there is an external side rudder, like on Viking ships.

The word comes from the Greek: thalassa = sea, kratein = to rule.

Thalassocracies had strong fleets and controlled sea routes, harbours, straits, and fjords. Their power was based on naval dominance.

Athens, Carthage, Venice, and the Portuguese Empire are all well-known examples of thalassocracies.

A Viking ship from the 4th century?

The Nydam find from the 4th century consisted of two ships, the larger of which, made of oak at 23 metres, is the one you see pictures of in this article.

The find, which was excavated around 1860, also includes hundreds of weapons such as swords, shields, and spears. Archaeologists have also unearthed a lot of personal equipment, tools, and supplies.

And they found runes – which tell of two men 1,700 years ago with names like Sikijar and Wagagastiz.

The Nydam find is today on display at the museum in Gottorf in the far north of Germany. It ended up there after the Danish-German war in 1864.

Perhaps both the large boathouses along the coast of Norway and the Nydam Ship found in Denmark are tangible evidence that the form of power the Vikings demonstrated between roughly 800 and 1050 had, to a large extent, already been developed around the year 300?

References:

Frans-Arne H. Stylegar: 'Thalassocracies of the North. Scandinavian naval bases and North Sea piracy in the 3rd and 4th centuries AD.' The article will be published in a coming book – a celebratory paper for archaeologist Dagfinn Skre.

Scandinavian Runic-text Database, Uppsala University.

Article about boathouse ruins by Frans-Arne Stylegar in the Great Norwegian Encyclopedia.

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Translated by Nancy Bazilchuk

Read the Norwegian version of this article on forskning.no