Proto-Indo-European homeland in the context of "Indo-European migrations"

Proto-Indo-European (PIE) is the reconstructed common ancestor of the Indo-European language family. No direct record of Proto-Indo-European has been discovered; its proposed features have been derived by linguistic reconstruction from documented Indo-European languages. Far more work has gone into reconstructing PIE than any other proto-language, and it is the best understood of all proto-languages of its age. The majority of linguistic work during the 19th century was devoted to the reconstruction of PIE and its daughter languages, and many of the modern techniques of linguistic reconstruction (such as the comparative method) were developed as a result.

PIE is hypothesized to have been spoken as a single language from approximately 4500 BCE to 2500 BCE during the Late Neolithic to Early Bronze Age, though estimates vary by more than a thousand years. According to the prevailing Kurgan hypothesis, the original homeland of the Proto-Indo-Europeans may have been in the Pontic–Caspian steppe of eastern Europe. The linguistic reconstruction of PIE has provided insight into the pastoral culture and patriarchal religion of its speakers. As speakers of Proto-Indo-European became isolated from each other through the Indo-European migrations, the regional dialects of Proto-Indo-European spoken by the various groups diverged, as each dialect underwent shifts in pronunciation (the Indo-European sound laws), morphology, and vocabulary. Over many centuries, these dialects transformed into the known ancient Indo-European languages. From there, further linguistic divergence led to the evolution of their current descendants, the modern Indo-European languages.

The Kurgan hypothesis (also known as the Kurgan theory, Kurgan model, or steppe theory) is the most widely accepted proposal to identify the Proto-Indo-European homeland from which the Indo-European languages spread out throughout Europe and parts of Asia. It postulates that the people of a Kurgan culture in the Pontic steppe north of the Black Sea were the most likely speakers of the Proto-Indo-European language (PIE). The term is derived from the Turkic word kurgan (курга́н), meaning tumulus or burial mound.

The steppe theory was first formulated by Otto Schrader (1883) and V. Gordon Childe (1926), then systematized in the 1950s by Marija Gimbutas, who used the term to group various prehistoric cultures, including the Yamnaya (or Pit Grave) culture and its predecessors. In the 2000s, David Anthony instead used the core Yamnaya culture and its relationship with other cultures as a point of reference.

Marija Gimbutas (Lithuanian: Marija Birutė Alseikaitė-Gimbutienė, pronounced ['ɡʲɪmbutas]; January 23, 1921 – February 2, 1994) was a Lithuanian archaeologist and anthropologist known for her research into the Neolithic and Bronze Age cultures of "Old Europe" and for her Kurgan hypothesis, which located the Proto-Indo-European homeland in the Pontic Steppe.

The Armenian hypothesis, also known as the Near Eastern model, is a theory of the Proto-Indo-European homeland, initially proposed by linguists Tamaz V. Gamkrelidze and Vyacheslav Ivanov in the early 1980s, which suggests that the Proto-Indo-European language was spoken during the 5th–4th millennia BC in "eastern Anatolia, the southern Caucasus, and northern Mesopotamia".

Recent ancient DNA research has led to renewed suggestions of a Caucasian homeland for a "pre-proto-Indo-European". Particularly, an admixture between the Khvalynsk and Caucasian Copper Age burials gave rise to the ancestry that later became known as a typical marker (WSH – Western Steppe Herders) of the Yamnaya pastoralists. It also lends support to the Indo-Hittite hypothesis, according to which both proto-Anatolian and proto-Indo-European split off from a common mother language "no later than the 4th millennium BCE".These suggestions have been disputed in other recent research, which still locates the origin of the ancestor of proto-Indo-European in the Eastern European/Eurasian steppe or from a hybridization of both steppe and Northwest-Caucasian languages. The origin of the Anatolian languages according to the Near Eastern model has also been challenged because "[a]mong comparative linguists, a Balkan route for the introduction of Anatolian IE is generally considered more likely than a passage through the Caucasus, due to, for example, greater Anatolian IE presence and language diversity in the west."