According to researchers from the Max Planck Institute for Evolutionary Anthropology, this was not a singular or uniform migration. Instead, the Slavic expansion unfolded through a range of regional patterns, replacing over 80% of the local gene pool in some areas while merging with native groups in others.
The emergence of the Slavs in the archaeological and written record has long posed questions for historians and geneticists alike. While early medieval texts begin to mention Slavic groups in the 6th century, especially around Constantinople and the Lower Danube, the mechanism behind their rapid spread remained unclear. Was it conquest, assimilation, or gradual migration?
This new genetic research, published in Nature, provides a more concrete picture of how the Slavic identity formed and spread. By sequencing genome-wide data from 555 ancient individuals across 26 sites, the study adds critical clarity to one of Europe’s most transformative historical periods.
Massive Population Turnover in Central Europe
The clearest sign of demographic change appears in regions like eastern Germany and Poland, where genetic signatures show overwhelming replacement of pre-existing populations. In the Elbe-Saale region of eastern Germany, for example, more than 85% of the genetic material from the post-Migration Period can be linked to newcomers from the East. This finding, reported by Sci.News, represents a dramatic break from earlier centuries, when the population exhibited more cosmopolitan ancestry, including strong ties to Northern Europe.
Poland tells a similar story. Starting in the 6th and 7th centuries CE, the region’s earlier inhabitants—who had strong Scandinavian genetic links—were almost entirely replaced by populations genetically similar to modern Poles, Ukrainians, and Belarusians. Though some traces of mixing with local groups remain, the general picture is one of large-scale replacement.
“The rise of the Slavs was, at its core, a story of people on the move,” said Dr. Joscha Gretzinger, one of the lead researchers behind the study. The genetic data line up with archaeological findings, especially the spread of small pit house settlements, cremation burials, and undecorated pottery known from the Prague-Korchak culture.
Social Structures Shaped by Kinship
One of the most striking findings of the study is how these migrating populations organized themselves socially. In eastern Germany, genetic analysis reveals tightly-knit communities built around patrilineal kinship groups. These large, extended families formed the backbone of early Slavic settlements, replacing the smaller, nuclear families typical of the Migration Period.
Women often left their birth villages to marry into other communities, further weaving a network of genetic connections across settlements. As stated by the researchers, this kinship model likely helped Slavic communities maintain cohesion and identity as they moved westward.
In contrast, areas such as Croatia display a more nuanced pattern. While there was a significant influx of eastern European ancestry, the genetic replacement was far from complete. Local traditions and social structures remained intact in many places, blending with those of the newcomers. This regional diversity points to a more flexible and adaptive process of cultural and genetic integration.
Lasting Legacy in Today’s Populations
Even today, the genetic imprint of these early Slavic migrations can still be detected. One example is the Sorbs, a Slavic-speaking minority in eastern Germany. Despite centuries of cultural and linguistic change around them, their genetic profile remains closely aligned with the early medieval Slavic settlers.
In the Balkans, too, the legacy of this demographic movement is visible, but in a more fragmented form. Genetic data from Croatia and neighboring regions show varying levels of eastern European ancestry, often making up only half or less of the modern gene pool. These findings suggest a long process of intermarriage and adaptation, rather than a swift replacement.
As noted by Dr. Zuzana Hofmanová of the Max Planck Institute, “Rather than a single people moving as one, the Slavic expansion was not a monolithic event but a mosaic of different groups, each adapting and blending in its own way.” The data support a picture of Slavic identity as multifaceted from the start, shaped by contact, migration, and local conditions.