But his genetic and physical inference from cases of ethnic durability cannot account for the considerable variability, wide range and frequent absorptions and dissolutions of instances of ethnic affiliation, and the fact that many ethnies have undergone large-scale changes of culture and, in some cases, of demography. This is the case even in such a culturally long-lived example as the Greeks, where undoubted evidence of massive rupture of demographic continuity by the influx of Albanians and Slavs on the Greek mainland from the sixth to eighth centuries AD and of considerable, though not complete, culture change after the conversion to Orthodoxy, call into question the continuity and influence of a common ancient Greek biological and genetic inheritance on modern Greeks.