They were preceded by a mixture of AASI (ancient ancestral south Indian, i.e. hunter-gatherers sharing a common root with the Andamanese); and Iranian agriculturalists who arrived in India ca. 4700–3000 BCE, and "must have reached the Indus Valley by the 4th millennium BCE". According to Narasimhan et al., this mixed population, which probably was native to the Indus Valley Civilisation, "contributed in large proportions to both the ANI and ASI", which took shape during the 2nd millennium BCE. ANI formed out of a mixture of ""Indus Periphery"-related groups" and migrants from the steppe, while ASI was formed out of ""Indus Periphery"-related groups" who moved south and mixed further with local hunter-gatherers. The ancestry of the ASI population is suggested to have averaged about 73% from the AASI and 27% from Iranian-related farmers. Narasimhan et al. observe that samples from the Indus periphery group are always mixes of the same two proximal sources of AASI and Iranian agriculturalist-related ancestry; with "one of the Indus Periphery individuals having ~42% AASI ancestry and the other two individuals having ~14-18% AASI ancestry" (with the remainder of their ancestry being from the Iranian agriculturalist-related population). A genetic study by Yelmen et al. (2019) shows that modern South Asian populations are generally closest to West-Eurasians. They concluded that modern South Asians are basically a mixture of a native South Asian genetic component and a later-arriving West-Eurasian component (derived from both West Asia and the western Steppes). The authors also argue that the native South Asian genetic component is distinct from the Andamanese, and that the Andamanese are thus an imperfect proxy. This component (when represented by the Andamanese Onge) was not detected in the northern Indian Gujarati, and thus it is suggested that the South Indian tribal Paniya people (a group of predominantly ASI ancestry) would serve as a better proxy than the Andamanese (Onge) for the "native South Asian" component in modern South Asians, as the Paniya are directly derived from the natives of South Asia (rather than distantly related to them as the Onge are). Two genetic studies (Shinde et al. 2019 and Narasimhan et al. 2019,) analysing remains from the Indus Valley civilisation (of parts of Bronze Age Northwest India and East Pakistan), found them to have a mixture of ancestry: Shinde et al. found their samples to have about 50-98% of their genome from peoples related to early Iranian farmers, and from 2-50% of their genome from native South Asian hunter-gatherers sharing a common ancestry with the Andamanese, with the Iranian-related ancestry being on average predominant.