Map of the Tujue Khanate (Ashina clan of Göktürks) at its greatest extent in 570
Situation of Interior Asia in Late 6th Century with approximate ranges of Eastern and Western Gokturks (Tujue)
Strictly speaking, the common name Göktürk is the Anatolian Turkish form of the ethnonym. The Old Turkic name for the Göktürks was 𐱅𐰇𐰼𐰰 Türük, 𐱅𐰇𐰼𐰰:𐰜𐰇𐰛 Kök Türük, or Türk. They were known in Middle Chinese historical sources as the tɦutkyat (Chinese: 突厥; pinyin: Tūjué). According to Chinese sources, the meaning of the word Tujue was "combat helmet" (Chinese: 兜鍪; pinyin: Dōumóu; Wade–Giles: Tou1-mou2), reportedly because the shape of the Altai Mountains where they lived, was similar to a combat helmet.
Göktürk means "Celestial Turks", or sometimes "Blue Turks" (i.e. because sky blue is associated with celestial realms). This is consistent with "the cult of heavenly ordained rule" which was a recurrent element of Altaic political culture and as such may have been imbibed by the Göktürks from their predecessors in Mongolia. The name of the ruling Ashina clan may derive from the Khotanese Saka term for "deep blue", āššɪna.
The word Türk meant "strong" in Old Turkic.