 The migration into northern India was not necessarily of a large population, but may have consisted of small groups, possibly of ethnically and genetically heterogeneous composition, who introduced their language and social system into the new territory.These were then emulated by larger groups, who adopted the new language and culture.Witzel also notes that "small-scale semi-annual
transhumance movements between the Indus plains and the Afghan and Baluchi highlands continue to this day."