On the basis of archaeological data between the 7th and 9th century, it is considered that the dating to the 7th century is generally reliable. Zdenko Vinski and V. V. Sedov supported it by the rare findings of objects and ceramics of the first small group of Slavs of the Prague-Korchak culture dated to the end of 6th and beginning of the 7th century, then of the most numerous and second group of Slavs (Antes) of the Prague-Penkovka culture with artifacts of Martinovka culture, while the related archaeological findings from the 8th-9th century indicate social-political stabilization and stratification. Another group of historians and archaeologists, like Lujo Margetić and Ante Milošević, argued late 8th-century migration as Frankish vassals during the Frank-Avar war (see Avar March), but it does not have enough evidence, it's not supported in written sources, and is not usually accepted. In the territory of present-day Croatia they gradually assimilated with the Pre-Slavic population as archaeological data does indicate some continuity of late antiquity population who mostly withdrew to the mountains, coastal cities and islands. However, the size and influence of the autochthonous population on the ethnogenesis is disputed depending on the interpretation of the archaeological data, considering them as a minority with some cultural influence or as a majority who outnumbered the Slavs.