🛡️ Two waves reshaped early medieval Europe

Genomes show that in the first half of the 1st millennium CE, at least two streams of Scandinavian-related ancestry spread into western, central, and eastern Europe. In Poland’s Wielbark horizon, models require >75% Early Iron Age Scandinavian ancestry, with some individuals near 100%. In the second half of the millennium, these northern ancestries diluted or disappeared through mixing.

Meanwhile, Scandinavia itself changed: by ~800 CE, especially in Denmark/southern Scandinavia, there’s a strong central-European–related influx not seen in earlier local Iron Age people, while Norway and northern Sweden show more continuity.

Takeaway: Early medieval Europe wasn’t static — first north-to-south expansions, then a backflow into Scandinavia, leaving layered ancestries across the continent.

Source: Speidel et al., 2025. High-resolution genomic history of early medieval Europe.