The first recorded use of the term “Türk” or “Türük” as an autonym is contained in the Old Turkic inscriptions of the Göktürks (Celestial Turks) of Central Asia (c. AD 735). The Turkic self-designation Türk is attested to reference to the Göktürks in the 6th century AD. A letter by Ishbara Qaghan to Emperor Wen of Sui in 585 described him as “the Great Turk Khan.”
An early form of the same name may be reflected in the form of tie-le (鐵勒) or tu-jue (突厥), a name given by the Chinese to the people living south of the Altay Mountains of Central Asia as early as 177 BC. The Chinese Book of Zhou (7th century) presents an etymology of the name Turk as derived from “helmet”, explaining that this name comes from the shape of a mountain where they worked in the Altai Mountains.
Greek and Latin sources
Pomponius Mela refers to the “Turcae” in the forests north of the Sea of Azov, and Pliny the Elder lists the “Tyrcae” among the people of the same area. The Greek name, Tourkia (Greek: Τουρκία) was used by the Byzantine emperor and scholar Constantine VII Porphyrogenitus in his book De Administrando Imperio, though in his use, “Turks” always referred to Magyars.
Similarly, the medieval Khazar Empire, a Turkic state on the northern shores of the Black and Caspian seas, was referred to as Tourkia (Land of the Turks) in Byzantine sources. However, the Byzantines later began using this name to define the Seljuk-controlled parts of Anatolia in the centuries that followed the Battle of Manzikert in 1071. The medieval Greek and Latin terms did not designate the same geographic area now known as Turkey.
Instead, they were mostly synonymous with Tartary, a term including Khazaria and the other khaganates of the Central Asian steppe, until the appearance of the Seljuks and the rise of the Ottoman Empire in the 14th century, reflecting the progress of the Turkic expansion. However, the term Tartary itself was a misnomer which was constantly used by the Europeans to refer the realms of Turkic peoples and Turkicized Mongols until the mid-19th century.
The Arabic cognate Turkiyya` (Arabic: تركيا) in the form ad-Dawlat at-Turkiyya (Arabic: الدولة التركية “State of the Turks” or “the Turkish State”) was historically used as an official name for the medieval Mamluk Sultanate which covered Egypt, Palestine, Syria, Hejaz and Cyrenaica.