Isotopes and human burials at Viking Age Birka and the Mälaren region, east central Sweden

Isotopic proveniencing has been applied to human inhumations and cremations as well as fauna from the Viking Age site of Birka and the surrounding Mälaren region, located in east-central Sweden. Human enamel from inhumations has been measured for strontium, oxygen, and carbon isotope ratios (petrous bone from cremations was measured for strontium only) to obtain information on mobility and diet. Seven graves from the larger Mälaren region and several at Birka had distinctive grave goods thought to have originated in Finland. The isotopic values from these graves indicate that they may have been local individuals. The faunal remains from the Mälaren region corresponded closely with samples from Birka providing a baseline for strontium isotopic ratios in this area. At the site of Birka, two distinct groups of burials can be identified among the measured values, along with several outliers. The data suggest that Birka was a multi-ethnic settlement in the Viking period, consistent with historical sources and concomitant with its role as an important center of economy and trade on the east coast of Sweden.