Workers made a surprising discovery in Poland when they pulled an early medieval sword from a muddy riverbed while dredging, and some researchers think the weapon could have a Viking connection.

Research is underway to learn more about the origins of medieval sword found earlier this month at the bottom of a Polish river, which some experts believe may have belonged to the Vikings.

We know that these so-called Ulfberht swords were produced somewhere in Central Europe, but it’s not known exactly where,” Sambor Gawiński from the Polish conservator office told local news.

Polish swords from the period were normally engraved on both sides with inscriptions and patriotic motifs, he added. “The sabre was probably the spoils of an officer of the Tsarist army who ...