DNA studies show that the first Polish Piast dynasty was also foreign. Like the Rurikids and Gediminids

Monument to Princes Mieszko I and Bolesław the Brave of the Piast Dynasty in the Golden Chapel in Poznań Cathedral

A group of geneticists and historians from the Institute of Bioorganic Chemistry of the Polish Academy of Sciences set out to create a comprehensive genetic portrait of the Piasts — the legendary ruling dynasty from which the recorded history of Poland begins.

The results of the study, which shatters historical myths, were published in April 2026 in Nature Communications.

The work began with the search for genuine remains among 340 presumed burial sites. Actual bone fragments were found in only 8 locations, from which 66 samples were extracted for ancient DNA. The main research site was the Cathedral of the Blessed Virgin Mary of Mazovia in Płock, where bones in the crypts were hopelessly mixed up during excavations in the 1970s. Old tags with kings' names did not correspond to reality, so scientists had to conduct an extensive cross-analysis.

To restore names to the bones, researchers compared historical chronicles with radiocarbon dating results and the ESA (Estimated Skeletal Age — the biological age of a person at the time of death, which anthropologists calculate based on the condition of teeth and skull sutures) indicator.

As a result of strict selection, scientists were able to obtain 17 high-quality male genomes, which they numbered from PIAST01 to PIAST17 and began a historical investigation.

Restoring Names

The identification process resembled assembling an extremely complex puzzle, where the main tool was the study of the Y-chromosome.

The uniqueness of this part of the human genome lies in the fact that it does not undergo recombination and is passed down exclusively through the male line from father to son in an almost unchanged form. This makes the Y-chromosome an ideal marker for tracking dynastic succession through dozens of generations, allowing for precise identification of direct descendants and revealing historical facts of biological lineage interruption.

Relying on this method, geneticists began to unravel the historical intricacies of the fates of the Piast dynasty's representatives. For instance, sample PIAST03 had a biological age indicator of about 25 years, which, together with the dating, perfectly matched the biography of Prince Leszek, who died in 1186 at the age of 21 to 26. The PIAST05 genome was precisely identified as Masovian Prince Konrad I (who died in 1247 at the age of about 60).

But the most interesting discoveries began with the study of kinship ties.

Павялічыць

Seal of Bolesław II of Masovia, who was first married to Gaudemunda, daughter of Grand Duke Traidenis of Lithuania. Photo: Wikimedia Commons

Software analysis showed that individual PIAST06, identified as Prince Bolesław II of Masovia (died in 1313), who was first married to Gaudemunda, daughter of Grand Duke Traidenis of Lithuania, had a first-degree kinship with sample PIAST11.

Since it is known from history that his son from his second marriage — Wenceslaus of Płock (died in 1336), husband of Elizabeth, daughter of Gediminas — was buried next to him, the identity of PIAST11 was confirmed beyond doubt. In turn, Wenceslaus demonstrated the same close connection with sample PIAST13, who turned out to be his own son, Bolesław III of Płock (died in 1351).

However, with sample PIAST09, everything was more complicated. The program showed its second degree of kinship with Bolesław II, which corresponds to a biological connection between grandfather and grandson.

According to documented data, this should have been one of his grandsons — Siemowit III of Masovia (died in 1381) or Casimir I of Warsaw (died in 1355). However, it turned out that PIAST09 had the male haplogroup R1a, while his grandfather Bolesław II belonged to haplogroup R1b.

This meant only one thing: the direct line of Y-chromosome transmission was interrupted because one of the wives in this chain gave birth to a child by another man.

The key to the genetic similarity lay in the maternal line, because the mother of this "grandson" had other representatives of the Piast lineage in her own genealogy. It was through the female line that individual PIAST09 inherited a quarter of the genome of his supposedly biological grandfather Bolesław II. Thus, through centuries, science is able to uncover even the most intimate family secrets of monarchs.

Not Slavs?

Павялічыць

The election of the plowman Piast as prince. Photo: Wikimedia Commons

Having dealt with the identification of the dynasty's representatives, scientists were able to look at the origin of the dynasty as a whole. According to the textbook legend, the first Polish state was created by a simple local plowman, Piast, from the Slavic Polans tribe. It was his historical descendant Mieszko I, who ruled approximately from 960 to 992, who officially brought his lands into pan-European politics through the adoption of Christianity in 966.

Павялічыць

Genealogical tree of the Piasts indicating the identified Y-chromosomal haplogroups. Photo: Nature Communications, 2026

However, genetics points to a completely different, less patriotic version of the origin of the Polish dynasty. Y-chromosome analysis revealed haplogroup R1b-BY3549 in the absolute majority of identified Piasts.

For the Slavic population of Central and Eastern Europe, this is an extremely rare lineage, which today is found predominantly in Great Britain. Consulting global paleogenome databases, researchers found only three ancient individuals with the same genetic marker, and all of them lived before the formation of the Polish state, definitely not on the banks of the Vistula.

Павялічыць

Heat map showing the frequency of Y-haplogroup R1b-P312 across modern Europe. Photo: Nature Communications, 2026

The first belonged to the Celtic Hallstatt culture and lived in France between 770 and 540 BC. The second rested in a Roman necropolis in the Netherlands during the period between 20 and 200 AD. The third was found in England and represented a 10th-century Viking (dated between 880 and 1000).

Apparently, the first Piasts had nothing in common with the local Slavs, but with a high degree of probability were newcomers of Germanic or Scandinavian origin. A well-armed military elite came from somewhere and subjugated the local tribes.

An additional indirect argument in favor of this conclusion is the economic foundation of the early state of Mieszko I and his son Bolesław I the Brave (ruled from 992 to 1025). The main source of income for the first Polish princes for a long time remained the slave trade on international markets, and this trade in the Early Middle Ages was firmly controlled precisely by the Vikings.

Female Diplomacy

Parallel to the male line, Polish researchers analyzed mitochondrial DNA, which is contained in cellular mitochondria and is transmitted exclusively from mother to all her children regardless of sex. This allowed them to trace the extent of European "female diplomacy" and resolve some historical questions with neighboring countries.

An excellent example was the unraveling of a dynastic mystery in Hungary. In 2012 in Budapest, the remains of King Béla III, who ruled from 1172 to 1196, and his wife Agnes of Antioch (1154—1184) were exhumed.

Павялічыць

19th-century drawing made during the excavation of King Béla III's burial. His burial is marked with the number I, his wife Agnes's with the number II, and his probable father's with the number III. Photo: Archaeological and Anthropological Sciences, 2019

Next to the royal couple, the bones of an unknown aristocrat were found, who had the same Y-chromosome as the king, but a completely different maternal line. Historians long debated to whom these remains belonged: the king's father or one of his grandsons.

The solution came thanks to the study of Polish graves. By comparing complex genealogies, geneticists found that the great-grandmother of the aforementioned Polish Prince Konrad I of Masovia was also the biological grandmother of Hungarian King Géza II (who ruled from 1141 to 1162).

Laboratory analysis showed that the unknown man from Budapest and Polish sample PIAST05 have a completely identical mitochondrial haplogroup T2b2b1. This genetic link allowed with 100% certainty to return the name of King Géza II to the unknown Hungarian remains.

Павялічыць

Genealogical tree demonstrating the connections between the Piast dynasty and the Hungarian royal house of Árpáds. Photo: Nature Communications, 2026

The same precise method worked with Anna of Bohemia (1204—1265), granddaughter of Béla III and Agnes of Antioch through their daughter Constance of Hungary (1180—1240). Anna was advantageously married to Polish Prince Henry II the Pious (1196—1241). When scientists opened her grave in modern Wrocław, the mitochondrial haplogroup H7b1 perfectly matched the genome of her grandmother Agnes.

Thanks to similar mathematical and biological cross-references, researchers indirectly calculated genetic markers for 108 Piasts, 32 Rurikids, 23 Árpáds, 15 Přemyslids, and 12 Gediminids.

This colossal dataset clearly proves that European politics was based not so much on the military power of men as on marriages.

The results of the Piast genome study brought about a previously impossible revolution in Polish historiography, which for centuries cherished the myth of the autochthony of its first dynasty.

Statehood in the Middle Ages had not an ethnic, but an exclusively dynastic-corporate character. The arrival of external military elites to power was an absolutely common situation in Europe: France was created by the Germanic Franks, England was conquered by the Normans, and Poland was united and christianized by some Celtic-Scandinavian newcomers, whose descendants, after several generations, fully adopted the local language and culture.

The blood of rulers did not determine their ethnic self-identification and did not change it in those they ruled; rather, the opposite was true: those they ruled determined what their rulers would become, their religion, and their language.

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