A genetic study published at bioRxiv in July 2019 and in "Nature" in September 2020 examined the population genomics of the Viking Age. 442 ancient humans from across Europe and the North Atlantic were surveyed, stretching from the Bronze Age to the Early Modern Period. In terms of Y-DNA composition, Viking individuals were similar to present-day Scandinavians. The most common Y-DNA haplogroup in the study was I1 (95 samples), R1b (84 samples) and R1a, especially (but not exclusively) of the Scandinavian R1a-Z284 subclade (61 samples). It was found that there was a notable foreign gene flow into Scandinavia in the years preceding the Viking Age and during the Viking Age itself. This gene flow entered Denmark and eastern Sweden, from which it spread into the rest of Scandinavia. The Y-DNA of Viking Age samples suggests that this may partly have been descendants of the Germanic tribes from the Migration Period returning to Scandinavia. The study also found that despite close cultural similarities, there were distinct genetic differences between regional populations in the Viking Age. These differences have persisted into modern times. Inland areas were found to be more genetically homogenous than coastal areas and islands such as Öland and Gotland. These islands were probably important trade settlements. Unsurprisingly, and very much consistent with historical records, the study found evidence of a major influx of Danish Viking ancestry into England, a Swedish influx into Estonia and Finland; and Norwegian influx into Ireland, Iceland and Greenland during the Viking Age.  The Vikings were found to have left a profound genetic imprint in the areas they settled, which has persisted into modern times with e.g. the contemporary population of the United Kingdom having up to 6% Viking DNA. The study also showed that some local people of Scotland were buried as Vikings and may have taken on Viking identities.