Ancient DNA research has become a widely applied method to examine past communities. The acidic soil in Finland has previously complicated archaeogenetic research but advances in the field have opened up new opportunities in recent years. This thesis integrates genetic data and archival research to examine the genetic ancestry and social organisation of Early Medieval communities in Southwest Finland. In this era, the coastal region of Southwest Finland experienced diverse societal changes induced by trade networks, urbanisation and conversion to Christianity. These shifts can be observed in large inhumation burial grounds from the Crusade Period (1025/1050–1150/1200 CE). While the burial grounds contain well-preserved skeletal material, no prior ancient DNA investigations have been undertaken in the area. A total of 30 individuals from three burial grounds, Tuomala, Kansakoulunmäki and Humikkala, were studied. The sites are located in the historical Raisio and Masku parishes close to Raisio river valley. The burial context was reconstructed with archival research, and the genetic data was extracted from skeletal samples. The resulting genome-wide data for 8 individuals from the Kansakoulunmäki burial ground was studied with exploratory population genetic and kinship analyses. The archival research produced a detailed burial context for 14 individuals from Kansakoulunmäki in Raisio and 15 individuals from Humikkala in Masku. The genetic results concluded good molecular preservation at Kansakoulunmäki and poor at Tuomala and Humikkala. The Kansakoulunmäki and Humikkala individuals bore traces of diverse connections to the Baltic Sea region. The integrated results revealed possible evidence of patrilocality and potential female genetic connections to Sigtuna in Central Sweden. These findings may point towards female mobility or exogamous marriage patterns between the two regions. Kinship relations were also detected. The possible sibling relationship could indicate an Early Medieval burial practice where close kin was buried together. The Kansakoulunmäki individuals appeared local and displayed genetic continuity with present-day Finns. This thesis adds to an emerging body of research on the ancient genetic compositions and social practices in coastal Southwest Finland in a period of transformation. The results underline the potential of interdisciplinary strategies combining genetic and archival research, as well as possibilities in the investigation of larger inhumation burial grounds. The study contributes to diverse lines of research with new data and interpretations about the Early Medieval communities, suggesting potential for further analyses both in Finland and across the Baltic Sea region.
free text keywords: Ancient DNA, archaeogenetics, archival research, genetic ancestry, social organisation, kinship, Early Medieval, Arkeologia, Archaeology, Arkeologi, Kulttuuriperinnön maisteriohjelma, Master's Programme in Cultural Heritage, Magisterprogrammet i kulturarv