Tracing the spread of Germanic languages using ancient genomics

Germanic languages, including German, English, Frisian, Dutch and the Nordic languages, are widely spoken across northwest Europe. However, the timing and location of the prehistoric arrival of this Indo-European linguistic phylum, as well as its Iron Age diversification, remain contentious^1-3. Here, by sequencing 712 ancient human genomes and analysing them alongside 4,009 previously published genomes, we identify an archaeologically elusive population that entered Sweden, likely from the Baltic region, by around 4000 BP. This population, which became widespread throughout Scandinavia by 3500 BP, offers a potential vector for the introduction of the Germanic language group to Scandinavia^4-6, some 800 years later than traditionally assumed^7-9. Following the Late Iron Age disintegration of Germanic into its descendant languages, we observe by 1650 BP a southward migration from southern Scandinavia into presumed Celtic-speaking areas, including present-day Germany, Poland and the Netherlands. During the subsequent Migration Period (1575-1375 BP), we see this ancestry among Germanic-speaking Anglo-Saxons in Britain and Langobards in southern Europe. In the same time period, we identify a related large-scale northward back-migration into Denmark and southern Sweden, coinciding with the rise of Danish influence and the linguistically documented emergence of Old Norse. These findings indicate that multiple migrations and geographical locations had a major role in the arrival and formation of Germanic, as well as in its divergence into historical and modern descendant languages.