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.

The sword sports a “mysterious inscription” and is one of eight weapons of its kind discovered so far in Poland, the Provincial Office for the Protection of Monuments in Toruń, a city near the spot where the sword was found and itself a protected world heritage site, wrote in a translated announcement on Facebook. Workers unearthed the sword from the bottom of Poland’s Vistula River while dredging the port at Włocławek, which is about 30 miles from Toruń.

Preliminary analyses of the weapon, having weathered centuries of corrosion, traced it back more than 1,000 years to the 10th century A.D., the culture office said. That period is significant for Poland, which did not exist prior to the formation that century of the House of Piast, the earliest known dynasty that settled in that area and began the first recorded reign over modern-day Polish land. Officials wondered in their announcement whether the sword may have borne witness to the formation of Polish statehood.