The latter part of the first millennium in Central and Eastern Europe witnessed profound cultural and political changes. This transformative era is typically linked to the emergence of the Slavs, supported by textual documentation and corresponding archaeological findings. However, there remains no agreement on whether this archaeological horizon spread through transition, a process termed “slabization,” or a mix of both. Notably, the prevalent cremation practices observed during the initial phases of slab settlements lack sufficient genetic data. In a recent investigation, scientists sequenced the genomes of 555 ancient individuals, including 359 samples from the Slavic context dating back to the 7th century AD. The new findings reveal significant population movements in Eastern Europe between the 6th and 8th centuries, which replaced over 80% of the local gene pools in areas such as East Germany, Poland, and Croatia.

The term “Slavs” first emerged to describe a nation in Constantinople during the 6th century and later gained recognition in the West.

Written records initially appeared north of the Lowward Now River and subsequently shifted to regions north of the Carpathian Basin, the Balkans, and the Eastern Alps.

Many areas were under the influence of the Avar Khaganate along the central Danube from around 567 AD to 800 AD.

Evidence indicates the presence of slab cultures in several regions of Eastern and Southeastern Europe during the 7th century.

Slavic settlements, previously inhabited by Roman, Germanic, and other pre-Slavic communities, transitioned to a simpler lifestyle, often represented archaeologically by small pithouse settlements, cremation burials, handmade and unembellished pottery, and a modest low-metal material culture associated with the Pragukorchak group.

Later, more sophisticated social structures and control emerged within the contact zone of the Byzantine-Christian West.

The Transformation of Europe by the Slavs

The first comprehensive ancient DNA analysis of medieval Slavic groups reveals that the rise of the Slavs was fundamentally a narrative of migration.

Their genetic signature points to origins in an area spanning southern Belarus to central Ukraine, aligning with longstanding linguistic and archaeological theories.

“Although direct evidence from the early Slavic core regions is still limited, our genetic findings provide initial substantial insights into the formation of Slavic ancestors, suggesting origins that may lie between the Donets and Don rivers.”

In this study, Dr. Gretzinger and colleagues gathered genome-wide data from 555 distinct ancient individuals from 26 sites throughout Central and Eastern Europe. They combined this with previously published data, creating comprehensive sampling networks for three regions.

New findings indicate that starting in the 6th century AD, large-scale migrations spread Eastern European ancestry throughout a vast area of central and eastern Europe, thus altering the genetic make-up of regions such as East Germany and Poland.

However, this expansion did not conform to a model of conquest or empire. Rather than obliterating existing military and structural hierarchies, newcomers founded new communities centered around extended families and patriarchal kinships.

This pattern was not uniform across all areas.

In eastern Germany, the changes were significant. Large, multi-generational lineages formed the backbone of society, and kinship networks became more broadly structured compared to the smaller nuclear families observed in earlier migration phases.

In contrast, areas such as Croatia experienced much less disruption in existing social patterns with the arrival of Eastern European groups.

Here, social structures often retained characteristics from previous periods, resulting in communities where new traditions harmonized with existing ones.

The regional diversity in social frameworks highlights that the spread of the Slavic group was not a one-size-fits-all process, but rather a dynamic adaptation to local contexts and histories.

“The expansion of the Slavs does not occur as a single event; it demonstrates that it is not a monolithic phenomenon, but each instance blends adaptation and integration according to its circumstances.”

East Germany

The genetic data reveals a particularly significant narrative in East Germany.

Following the decline of the Kingdom of Thuringia, more than 85% of the region’s ancestry can be traced back to new arrivals from the east.

This reflects a shift from an earlier period of diverse populations, as epitomized by the Brucken site.

With the rise of the Slavs, this diversity gave way to a population composition resembling that of modern Slavic-speaking groups in Eastern Europe.

These new communities were structured around large extended families and patriarchal lineages, with women of marriageable age often moving to form new households elsewhere, leaving their native villages.

Notably, the genetic heritage of these initial Eastern European settlers is still present among the Sorbs, the Slavic-speaking minority in East Germany.

Amidst centuries of cultural and linguistic changes, Sorbs maintain genetic profiles closely related to early medieval Slavic populations that settled in the region over a millennium ago.

Poland

In Poland, research notably challenges previous assumptions regarding long-standing population continuity.

Genetic findings indicate that early inhabitants of the region, beginning in the 6th and 7th centuries AD—especially descendants of a population closely tied to Northern Europe and Scandinavia—were nearly completely replaced by newcomers from the East, closely related to modern Poles, Ukrainians, and Belarusians.

While overwhelming population shifts occurred, genetic evidence also reveals small traces of intermingling with local populations.

These insights underscore both the magnitude of population change and the intricate dynamics shaping the ancestry of present-day Central and Eastern European languages.

Croatia

In Northern Balkans, the patterns observed differ markedly from those in northern immigrant regions, narrating a tale of both transformation and continuity.

Ancient DNA analyses from Croatia and surrounding areas illustrate a significant influx of ancestors from Eastern Europe, yet without total genetic replacement.

Instead, Eastern European immigrants integrated with diverse local populations to form hybrid communities.

Genetic studies show that in modern Balkan populations, the proportion of Eastern European ancestry varies significantly, often reaching around half or less of the current genetic mix.

In this context, Slavic migration wasn’t characterized by conquest but was a gradual process of intermarriage and adaptation, leading to the rich cultural, linguistic, and genetic diversity that defines the Balkans today.

A New Chapter in European History

In most instances, when early Slavic groups are referenced in archaeological and historical contexts, their genetic markers are consistent, indicating a shared ancestral origin, though regional variations reflect the extent of blending with local populations.

In the north, early Germanic communities mostly left, providing space for Slavic integration.

In the south, Eastern European migrants merged with established societies.

This patchwork integration elucidates the remarkable diversity present in the cultures, languages, and genetics of contemporary Central and Eastern European societies.

“The spread of the Slavs was likely the last significant demographic event to irreversibly reshape both the genetic and linguistic landscapes of Europe,” remarked Dr. Johannes Kraus, director of the Max Planck Institute for Evolutionary Anthropology.

The findings were published in the journal on September 3rd Nature.

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J. Gretzinger et al. Ancient DNA connects large-scale migration with the spread of the Slavs. Nature, published online on September 3, 2025. doi:10.1038/s41586-025-09437-6

This article is adapted from the original release by the Max Planck Institute for Evolutionary Anthropology.