The scholars of the 19th century who first tackled the question of the Indo-Europeans' original
homeland (also called Urheimat , from German), had essentially only linguistic evidence. They attempted
a rough localization by reconstructing the names of plants and animals (importantly the beech and
the salmon) as well as the culture and technology (a Bronze Age culture centered on animal husbandry
and having domesticated the horse). The scholarly opinions became basically divided between a
European hypothesis, positing migration from Europe to Asia, and an Asian hypothesis, holding that the
migration took place in the opposite direction.
In the early 20th century, the question became associated with the expansion of a supposed "Aryan
race", a now-discredited theory promoted during the expansion of European empires and the rise of
"scientific racism".[13] The question remains contentious within some flavours of ethnic nationalism (see
also Indigenous Aryans).
A series of major advances occurred in the 1970s due to the convergence of several factors. First,
the radiocarbon dating method (invented in 1949) had become sufficiently inexpensive to be applied on
a mass scale. Through dendrochronology (tree-ring dating), pre-historians could calibrate radiocarbon
dates to a much higher degree of accuracy. And finally, before the 1970s, parts of Eastern Europe and
Central Asia had been off limits to Western scholars, while non-Western archaeologists did not have
access to publication in Western peer-reviewed journals. The pioneering work of Marija Gimbutas,
assisted by Colin Renfrew, at least partly addressed this problem by organizing expeditions and
arranging for more academic collaboration between Western and non-Western scholars.
The Kurgan hypothesis, as of 2017 the most widely held theory, depends on linguistic and archaeological
evidence, but is not universally accepted.[14][15] It suggests PIE origin in the Pontic–Caspian steppe during
the Chalcolithic.[16] A minority of scholars prefer the Anatolian hypothesis, suggesting an origin
in Anatolia during the Neolithic. Other theories (Armenian hypothesis, Out of India theory, Paleolithic
continuity theory, Balkan hypothesis) have only marginal scholarly support.[16]
In regard to terminology, in the 19th and early 20th centuries, the term Aryan was used to refer to the
Proto-Indo-Europeans and their descendants. However, Aryan more properly applies to the Indo-
Iranians, the Indo-European branch that settled parts of the Middle East and South Asia, as only Indic
and Iranian languages explicitly affirm the term as a self-designation referring to the entirety of their
people, whereas the same Proto-Indo-European root (*aryo-) is the basis for Greek and Germanic word
forms which seem only to denote the ruling elite of Proto-Indo-European (PIE) society. In fact, the most
accessible evidence available confirms only the existence of a common, but vague, socio-cultural
designation of "nobility" associated with PIE society, such that Greek socio-cultural lexicon and
Germanic proper names derived from this root remain insufficient to determine whether the concept
was limited to the designation of an exclusive, socio-political elite, or whether it could possibly have
been applied in the most inclusive sense to an inherent and ancestral "noble" quality which allegedly
characterized all ethnic members of PIE society. Only the latter could have served as a true and universal
self-designation for the Proto-Indo-European people.[17][18]
By the early twentieth century, this term had come to be widely used in a racist context referring to a
hypothesized white, blonde and blue-eyed "master race" ( Herrenrasse ), culminating with the pogroms
of the Nazis in Europe. Subsequently, the term Aryan as a general term for Indo-Europeans has been
largely abandoned by scholars (though the term Indo-Aryan is still used to refer to the branch that
settled in Southern Asia).[19]