Proto-Turkic language

The Proto-Turkic language is the reconstructed proto-language of the family of Turkic languages that predates the separation of the Turkic peoples and separation into Oghuz and Oghur branches.

The oldest records of a Turkic language, the Old Turkic Orkhon inscriptions of the 7th century Göktürk khaganate, already show characteristics of the Eastern branch of Turkic, and reconstruction of Proto-Turkic must rely on comparisons of Old Turkic with early sources of the Western branches, Oghuz and Kypchak, as well as the Oghur branch (Bulgar, Chuvash, Hunnic, Khazar). Because attestation of these non-Eastern languages is much more sparse, reconstruction of Proto-Turkic still rests fundamentally on East Old Turkic of the Göktürks.

Phonology

Proto-Turkic exhibited vowel harmony, a feature sometimes also ascribed to the so-called Proto-Altaic, distinguishing vowel qualities e, i, o, u vs. ë, ï, ö, ü besides a, as well as two vowel quantities.

The consonant system had a two-way contrast of stop consonants (fortis vs. lenis), k, p, t vs. g, b, d, with verb-initial b- becoming h- still in Proto-Turkic. There was also an affricate consonant, č; at least one sibilant s; and sonorants m, n, ń, ŋ, r, ŕ, l, ĺ with a full series of nasal consonants.