A monograph based on Chinese sources and historical literature examines Chinese transcriptions of the Turk ethnonym from the second millennium BC to the 7th century AD; the name of the Turk tribe (Tujue) and its migration routes; etymology and localization of the ethnonym ruziye (yuezhi); the ethnic origin of the Yaypans and Hephthalites, as well as some debatable issues related to these ethnonyms.