Sometime between 1031 and 1147, a woman was buried at Laukskola, a cemetery on the Daugava River in Latvia. Her community probably spoke Liv, a Finnic language that has nearly died out, and its grave goods are rich enough that archaeologists tie its wealth to the trading places along the river. Her genome, already published, turns up in a new analysis with long stretches of DNA that match two people buried in Finland in roughly the same period. One was buried at Raisio, on the edge of Turku near the southwest coast. The other was a parent buried at Mikkola, in the inland municipality of Ylöjärvi, at the same site as three of that parent’s children. The amount of DNA involved puts both relationships at sixth cousins or more distant, implying an ancestor some generations back who crossed between Latvia and southwestern Finland in one direction or the other.
The Latvian woman’s kin sit on either side of a line that Finnish archaeology has long drawn through the southwest. The coastal zone, today’s regions of Varsinais-Suomi and Satakunta, already had the strongest material ties to Scandinavia in the Viking Age, while inland Häme had a mixed profile, with objects and customs from both west and east. Finland’s Swedish-speaking minority, the Finlandssvenskar, is concentrated on the coast today. Add the name this era long carried in Finnish history, the Crusade Period, and most readers assemble the same picture: a coast that was always the more Scandinavian place, made more so when Swedish expeditions crossed the Baltic to convert and conquer the Finns.
A study published on September 15, 2026, in Genome Biology1 argues that the picture gets the timing wrong. In the Early Medieval period, which in Finland runs from 1050 to 1250 CE, people on the coast and people in Häme were genetically one population, and the extra Scandinavian ancestry that sets the coast apart today arrived mostly after 1250, through migration from Sweden that largely stopped short of the interior. The team, led by Ronan James O’Sullivan of the University of Turku’s Department of Biology, with Sanni Peltola and Päivi Onkamo as shared senior authors, generated genome-wide data for 38 people from 17 archaeological sites and set aside four whose contamination could not be reliably measured. Of the remaining 34, 32 date to the Early Medieval period and 2 to the Late Iron Age, 800 to 1050 CE. Only 26 ancient genomes of comparable quality had been published from Finland before, against thousands from elsewhere in northern Europe; the country’s acidic soil breaks down unburnt bone fast.
The authors avoid the Crusade Period label. Most modern scholars regard the three Swedish crusades to Finland as literary constructions of the later Middle Ages, and whatever papally sanctioned fighting took place was probably small and aimed at consolidating Swedish rule; no account written from inside Early Medieval Finland survives, and the sources that do exist, such as the Novgorod Chronicles and the legend of Saint Erik, were written by outsiders.
