In modern times, Scandinavian countries have gained a reputation for their sometimes uneasy acceptance of migrants from the Arab and Muslim world. But the roots of this relationship go back much further than you might think.

Take, for instance, a ring found in a Viking grave in Birka, an ancient trading hub in what is now Sweden. The woman buried there lived in the 9th century, and her grave was unearthed about a thousand years later by the renowned Swedish archaeologist Hjalmar Stolpe, who spent years exploring burial sites around Birka.

This ring is quite special. It's made of a silver alloy and features a stone with an inscription in the Kufic Arabic script, commonly used between the 8th and 10th centuries. The inscription reads "For/to Allah." It's the only Viking Age ring found in all of Scandinavia with an Arabic inscription. How the woman acquired the ring isn't entirely clear – she was found dressed in typical Scandinavian clothing, so it's likely it came through trade.

Recent research by biophysicist Sebastian Wärmländer of Stockholm University and his team has shed more light on just how unique this ring is. Using a scanning electron microscope, they examined the ring and discovered that the stone is actually colored glass – a material exotic to the Vikings but long made in the Middle East and North Africa.

What's particularly interesting is that the ring shows little signs of wear, suggesting it may have had few, if any, owners between its creation and the Viking woman who wore it. This suggests a direct connection between Viking society and the Abbasid Caliphate in the Middle East and North Africa. Wärmländer and his colleagues speculate that the woman herself, or someone close to her, might have traveled from or had origins in the Caliphate or its surrounding areas.

While physical evidence like this is rare, there are many accounts of Scandinavians from that era encountering the early Muslim world. By the 11th century, Vikings were known for their extensive sea voyages, reaching as far as the Americas and possibly even Constantinople and Baghdad in the east. Though they were often portrayed as fearsome invaders, most accounts suggest they were primarily interested in trade during their eastern travels.

"The Vikings were very fond of silver, less so of gold," explained historian Farhat Hussain. "Silver was a symbol of status for Viking men and women, and they even desired to be buried with it."

However, the Scandinavians did attract some attention during their travels. Ahmad ibn Fadlan, an emissary of the Abbasid Caliph, described them in the 10th century as lacking in hygiene. "They are the dirtiest of all creatures," he wrote. "They do not cleanse themselves after using the bathroom or wash after intimate relations, nor do they wash their hands after eating."

As for how the woman in Birka and the ring fit into this historical relationship, it remains a mystery. Linda Wåhlander, a teacher at the Statens historiska museum who worked on the project, expressed her curiosity, saying, "I don't know if it was bought or taken by force, and of course, I wish I knew the circumstances of how this woman came to possess it – whether it was a friendly exchange or not, whether she traveled far from home, or if someone brought it back for her. I am an archaeologist, but sometimes I wish I could travel through time."