Who was in Harold Bluetooth's army? Strontium isotope investigation of the cemetery at the Viking Age fortress at Trelleborg, Denmark

Abstract
The circular fortress of Trelleborg on Zealand in Denmark is well known as a military camp with a key role in the formation of the Danish state under Harald Bluetooth in the tenth century AD. Taking a sample of 48 burials from the fort, strontium isotope analysis once again demonstrates its ability to eavesdrop on a community: at Trelleborg, the young men in its cemetery were largely recruited from outside Denmark, perhaps from Norway or the Slavic regions. Even persons buried together proved to have different origins, and the three females sampled were all from overseas, including a wealthy woman with a silver casket. Trelleborg, home of Harald Bluetooth's army, was a fortress of foreigners with vivid implications for the nature of his political mission.