Today, Teisen in Oslo is a typical residential area with low-rise apartment buildings and detached houses. But for many centuries, it was farmland.
It may have been a Teisen farmer who buried a large silver treasure here sometime after 919 CE. That is the date on the youngest Islamic coin in the Teisen treasure, according to the Museum of the Viking Age.
The hoard consists of intricate silver jewellery, hacksilver, and lots of silver coins – with Arabic script.
They are called dirhams.
Enormous quantities of coins
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The coins originate from the Islamic Caliphate, which existed from around the year 700 and lasted for centuries in various forms – also known as the Abbasid Caliphate.
It covered vast areas of what are now North Africa, the Middle East, and the Arabian Peninsula.
And it existed right in the middle of the Viking Age.
You might assume Islamic silver coins would be rare this far north. But across Norway, Sweden, and eastward into Russia, they appear in astonishing numbers.
This is the Teisen treasure.(Photo: Museum of Cultural History, University of Oslo / Eirik Irgens Johnsen)
A billion silver dirhams may have reached the Viking world, according to coin researcher Svein H. Gullbekk.(Photo: Lasse Biørnstad / Science Norway)
Swedish archaeology professor Martin Rundkvist described this in a 2024 article:
'It seems that if you send 25 detectorists
onto the land of a farm in agricultural southern
Sweden for three days and keep them from moving around too much, they always find a few dirham coins.'
The sheer volume of Kufic-script coins that reached Scandinavia is almost unimaginable. Kufic is an early, angular form of Arabic calligraphy.
It is often called Islamic silver because it relates to both the religion and script in this region, according to Svein H. Gullbekk. He is a numismatist – meaning a coin researcher – and a professor at the University of Oslo.
Far fewer dirhams have been found in Norway than in Sweden, where the island of Gotland is in a class of its own.
But they made their way to Norway as well.
They have been found in settlements, marketplaces, buried treasures, and scattered around where people lived. The Norse must have been well acquainted with these coins with mysterious inscriptions.
"But as far as we know, there were none or very few who could actually understood the symbols on the coins," Svein H. Gullbekk tells Science Norway.
A mystery in the world of coins
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"Perhaps a billion silver dirhams flowed into Scandinavia and the Viking world between 800 and 950," says Gullbekk.
That figure is based in part on the number of dirhams unearthed in Sweden and farther east.
Gullbekk has led us to the secured coin collection at the Historical Museum, though we’re not permitted to enter the room where the coins are kept.
"Here you see part of the driving force behind the Viking Age," says the coin expert as he brings out a tray of silver coins.
The desire to bring home high-quality silver may have inspired people to venture out from Scandinavia.
"Young men sought wealth, and silver was one of the best ways to gain it," he says.
Decades of research indicate that Vikings primarily traded furs and slaves, as well as animal hides and reindeer antlers. And they received silver in return.
Some of that silver likely also came from Europe, particularly from the Carolingian Empire in Central Europe, says Gullbekk.
A selection of dirhams from the coin cabinet at the Historical Museum.(Photo: Lasse Biørnstad / Science Norway)
"We know this from written sources and the coins themselves," he says.
The coins were cut up
European silver coins are much rarer in Scandinavia. This is a mystery in the world of numismatics, says Gullbekk.
He shows one of the dirhams kept in the Historical Museum's collection, found at Grimestad, Eastern Norway, in 1936.
This coin comes from the city of Tashkent and dates to between 907 and 914, during the reign of Amir Ahmad ibn Ismail.
He ruled the Samanids – a people and great empire that stretched across parts of what is now Iran.
"It weighs about two and a half grams," says Gullbekk.
The coin feels heavier than expected. The Kufic inscription is still clearly visible.
Some of the silver was used as currency, at least in parts of present-day Norway.
"Many of these coins were cut into small pieces, and some were melted down," says Gullbekk.
That was because the value was determined by the silver's weight. Both coins and other silver pieces were cut up, known as hacksilver.
An example of a dirham cut into pieces.(Photo: Trond Sverre Skevik / CC BY-SA 4.0)
Could this silver also have been used to craft exquisite objects? A British research team is working to identify the chemical signature of the Islamic silver and other silver that ended up in Viking hands.
Their findings suggest that some of it was transformed into the most precious Viking treasures.
Some wanted to check if the silver was fake
The photo below shows a large hoard discovered in 2012 with a metal detector in Bedale, England.
It consists of Viking jewellery, numerous small silver bars, and an Anglo-Saxon sword. The hoard partly originates from Viking Scandinavia but also from local English areas.
The Bedale Hoard from England. The silver bars are at the back.(Photo: York Museums Trust / CC BY 4.0)
The small bars are melted silver – shaped into standardised pieces used for trade.
Many of them are covered in tiny notches, likely made by curious hands over the centuries.
"The Vikings tested the quality of the silver by cutting into it," Gullbekk says, referring to these marks, known from many other Viking silver finds.
Some wanted to be sure the silver they held was real, not a clever forgery.
Svein H. Gullbekk looks at a tray of dirhams.(Photo: Lasse Biørnstad / Science Norway)
Some silver has been recycled so many times that its original source has been erased. Gullbekk notes that some may even have circulated since Alexander the Great minted coins in the 4th century BCE.
The researchers' analyses suggest that the silver in the jewellery and bars from the British hoard comes mainly from three sources:
A large portion from Europe, a significant amount from mines within Islamic realms, and the rest a mixture.
The researchers argue that the European silver likely comes from melted-down coins, possibly taken as war booty from Western Europe and the Carolingian Empire.
"That's incredibly interesting," says Gullbekk. “If we can trace where the silver originated, we can uncover vivid details about trade routes and the goods exchanged. It helps us form a clearer picture of large-scale movements in society."
The findings suggest that some Islamic dirhams were melted down and re-forged into jewellery.
Could there be Islamic silver in jewellery and hoards from the Viking Age?
The Samanid Mausoleum in Bukhara, present-day Uzbekistan.(Photo: Shutterstock / NTB)
Proof: "A fantastic find"
"We have an absolutely fantastic find from the trading site at Sikringssal," says Gullbekk.
He refers to a half-melted lump of silver excavated from the ancient settlement outside Larvik in the early 2000s.
A handful of half-melted dirhams protrude from the silver mass.
" It’s tangible proof that dirhams were melted down. They were probably used for jewellery or other silverwork," he believes.
In time, these methods may reveal the origins of the silver found in Norwegian Viking Age hoards.
A lump of silver with half-melted dirhams.(Photo: Eirik Irgens Johnsen & Kirsten Helgeland / CC BY-SA 4.0)
"The finest silver"
Frans-Arne Stylegar, an archaeologist at Multiconsult, believes the Vikings turned this silver into jewellery because they valued it highly. He has written a text about Islamic silver on his blog (link in Norwegian).
"I think they knew exactly where the finest silver came from. To find it, you had to go far to the southeast – not to France or England," he believes.
Stylegar explains that much of this silver travelled along long trade routes.
"There's no doubt that Norwegians travelled all the way to the Caspian Sea to get these coins. From there, the silver moved north into Russia, Sweden, parts of Denmark, and especially Eastern Norway," he says.
Stylegar points out that analyses of the British hoard suggest that not much Islamic silver reached that region.
By contrast, Scandinavian jewellery may have been crafted from more Islamic silver, he believes.
As for the distribution of dirham finds within Norway, Stylegar says we still know too little. Many discoveries made with metal detectors have yet to be properly catalogued or studied.
