Proto-Turkic language

Proto-Turkic is the linguistic reconstruction of the common ancestor of the Turkic languages that was spoken by the Proto-Turks before their divergence into the various Turkic peoples. Proto-Turkic separated into Oghur (western) and Common Turkic (eastern) branches. Candidates for the Proto-Turkic homeland range from western Central Asia to Manchuria, with most scholars agreeing that their migrations started from the eastern part of the Central Asian steppe, while one author has postulated that Proto-Turkic originated 2,500 years ago in East Asia.

The oldest records of a Turkic language, the Old Turkic Orkhon inscriptions of the 7th century Göktürk khaganate, already show characteristics of Eastern Common Turkic. For a long time, the reconstruction of Proto-Turkic relied on comparisons of Old Turkic with early sources of the Western Common Turkic branches, such as Oghuz and Kypchak, as well as the Western Oghur proper (Bulgar, Chuvash, Khazar). Because early attestation of these non-easternmost languages is much sparser, reconstruction of Proto-Turkic still rests fundamentally on the easternmost Old Turkic of the Göktürks, however it now also includes a more comprehensive analysis of all written and spoken forms of the language.

The Proto-Turkic language shows evidence of influence from several neighboring language groups, including Eastern Iranian, Tocharian, and Old Chinese.

There is general agreement among linguists and historians that Proto-Turkic was spoken somewhere in Central-East Asia. Its most likely ultimate homeland was modern-day Eastern Mongolia. From circa 1200 BCE, nomadic activity led to the expansion of Proto-Turkic into a wider area, from the Sayan-Altai Mountains in South Siberia, to Eastern Inner Mongolia. Proto-Turkic is thought to have split at the end of the first millennium BCE.

The likely ultimate homeland of Proto-Turkic in Eastern Mongolia was very close to the homeland of the Proto-Mongolic language in Southern Manchuria and the homeland of Proto-Tungusic in the area where modern-day China, Russia and North Korea meet, which would explain the proximity of these languages.

The consonant system had a two-way contrast of stop consonants (fortis vs. lenis), k, p, t vs. g, b, d. There was also an affricate consonant, č; at least one sibilant s and sonorants m, n, ń, ŋ, r, l with a full series of nasal consonants. Some scholars additionally reconstruct the palatalized sounds ĺ and ŕ for the correspondence sets Oghuric /l/ ~ Common Turkic *š and Oghuric /r/ ~ Common Turkic *z. Most scholars, however, assume that these are the regular reflexes of Proto-Turkic *l and *r. Oghuric is thus sometimes referred to as Lir-Turkic and Common Turkic as Shaz-Turkic.

A glottochronological reconstruction based on analysis of isoglosses and Sinicisms points to the timing of the r/z split at around 56 BCE–48 CE. As Anna Dybo puts it, that may be associated with

the historical situation that can be seen in the history of the Huns' division onto the Northern and Southern [groups]: the first separation and withdrawal of the Northern Huns to the west has occurred, as was stated above, in 56 BC,... the second split of the (Eastern) Huns into the northern and southern groups happened in 48 AD.