 One estimate postulates Proto-Turkic to have been spoken 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 and reconstruction of Proto-Turkic must rely 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.