In which country did a 5th century CE massacre take place in this fort?

Founded around 480 CE and excavated beginning in 2010 is an Iron Age ring fort, one of at least 15, located on the island of Oland, in Sweden. It sits about 2 kilometers (1.24 miles) southeast of Sodra Sandby village in Sandby parish in southeastern Oland, nearby Gardby.

A ring fort is a circular fortified settlement made of stone or earth.

The fort has been the subject of archeological excavations where researchers have determined it was the scene of a massacre in the late 5th century CE. The victims of the massacre were never buried, but were found lying as they fell, inside the houses and scattered on the streets of the fort. Excavations are continuing as of 2022.

As a result of this finding at Sandby, the massacre event provides new insights both to violence and conflict in the Iron Age, and concerning everyday life in the ring fort.

Aerial photographs and geophysical surveys of the ring fort interior revealed buried stone structures, interpreted as the stone house walls of 53 houses.

The walls were made from local limestone with a fill of erratic boulders that are not from the area plus pebbles. Three gates are visible as shallow depressions in the wall; crop marks from aerial shots of the site suggest the possible presence of a fourth gate. The original ring fort was 4 meters wide (13.12 feet) and the walls are estimated to have been 4-5 meters (13.12-16.4 feet) high.

It is unknown why the massacre occurred.