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 it lay in 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 shows 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 more sparse, 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. Phonology Consonants 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, ç; at least one sibilant s and sonorants m, n, ń, ŋ, r, ŕ, l, ĺ with a full series of nasal consonants. The sounds denoted by ń, ĺ, ŕ refer to palatalized sounds and have been claimed by Altaicists to be direct inheritances from Proto-Altaic. The last two can be reconstructed with the aid of the Oghur languages, which show for *ŕ, *ĺ, while Common Turkic has *z, *š. Oghuric is thus sometimes referred to as Lir-Turkic and Common Turkic as Shaz-Turkic. However, an alternate theory holds that Common Turkic is closer to the original state of affairs and reconstructs Proto-Turkic *z, *š. The 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 A. V. 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