It is considered that I-L621 could have been present in the Cucuteni–Trypillia culture, but until now was only found G2a, and another subclade I2a1a1-CTS595 was present in the Baden culture of the Calcholitic Carpathian Basin. Although it is dominant among the modern Slavic peoples on the territory of the former Balkan provinces of the Roman Empire, until now it was not found among the samples from the Roman period and is almost absent in contemporary population of Italy. It was found in the skeletal remains with artifacts, indicating leaders, of Hungarian conquerors of the Carpathian Basin from the 9th century, part of Western Eurasian-Slavic component of the Hungarians. According to Horolma "et al." (2019) and Fóthi "et al." (2020), the distribution of ancestral subclades like of I-CTS10228 among contemporary carriers indicates a rapid expansion from Southeastern Poland, is mainly related to the Slavs and their medieval migration, and the "largest demographic explosion occurred in the Balkans". The earliest archeogenetic sample until now is Sungir 6 (~900 YBP) near Vladimir, Russia which belonged to the I-S17250 &gt; I-Y5596 &gt; I-Z16971 &gt; I-Y5595 &gt; I-A16681 subclade, as well I-CTS10228 and I-Y3120 subclades were found in two Viking samples from Sweden (VK53) and Ukraine (VK542) with predominantly Slavic ancestry of which the second belongs to Gleb Svyatoslavich (11th century).