The Proto-Indo-Europeans are a hypothetical prehistoric population of Eurasia who spoke Proto-Indo-European (PIE), the ancestor of the Indo-European languages according to linguistic reconstruction. Knowledge of them comes chiefly from that linguistic reconstruction, along with material evidence from archaeology and archaeogenetics. The Proto-Indo-Europeans likely lived during the late Neolithic, or roughly the 4th millennium BC. Mainstream scholarship places them in the Pontic–Caspian steppe zone in Eurasia (present-day Ukraine and southern Russia). Some archaeologists would extend the time depth of PIE to the middle Neolithic (5500 to 4500 BC) or even the early Neolithic (7500 to 5500 BC) and suggest alternative location hypotheses. By the early second millennium BC, descendants of the Proto-Indo-Europeans had reached far and wide across Eurasia, including Anatolia (Hittites), the Aegean (the linguistic ancestors of Mycenaean Greece), the north of Europe (Corded Ware culture), the edges of Central Asia (Yamnaya culture), and southern Siberia (Afanasievo culture). Definition In the words of philologist Martin L. West, "If there was an Indo-European language, it follows that there was a people who spoke it: not a people in the sense of a nation, for they may never have formed a political unity, and not a people in any racial sense, for they may have been as genetically mixed as any modern population defined by language. If our language is a descendant of theirs, that does not make them ‘our ancestors’, any more than the ancient Romans are the ancestors of the French, the Romanians, and the Brazilians. The Indo-Europeans were a people in the sense of a linguistic community. We should probably think of them as a loose network of clans and tribes, inhabiting a coherent territory of limited size." While 'Proto-Indo-Europeans' is used in scholarship to designate the group of speakers associated with the reconstructed proto-language and culture, the term 'Indo-Europeans' may refer to any historical people that speak an Indo-European language. Culture Using linguistic reconstruction from old Indo-European languages such as Latin and Sanskrit, hypothetical features of the Proto-Indo-European language are deduced. Assuming that these linguistic features reflect culture and environment of the Proto-Indo-Europeans, the following cultural and environmental traits are widely proposed: pastoralism, including domesticated cattle, horses, and dogs agriculture and cereal cultivation, including technology commonly ascribed to late-Neolithic farming communities, e.g., the plow transportation by or across water the solid wheel, used for wagons, but not yet chariots with spoked wheels worship of a sky god, *Dyḗus