The Chigil (Chihil, and also (D)Jigil, Cihil, Chiyal) were a Turkic tribe known from the 7th century CE as living around Issyk Kul lake area. They were considered to be descended from the tribe Chuyue, who were of mixed Yueban-Western Turkic origins.
Sinologist Yu. A. Zuev notes that the Chinese transcription of Chigil, 處月 Chǔyuè (Middle Chinese (ZS): /t͡ɕhɨʌx-ŋʉɐt̚/) may be calqued as "abode of the Moon [god]"; whereas 處密 Chǔmì (/t͡ɕhɨʌx-mɣiɪt̚/)) as "abode of the Sun [god]", for Chinese 密 transcribed Middle Iranian theonym Mihr, the all-seeing Zoroastrian deity of covenent, oath, and light, vaguely associated with the Sun. However, citing Gabain's 1931 and 1934 researches, Zuev cautions that neither Turkic-Buddhist texts, nor the Turkic-Manichaean literature and other sources containing information about Turkic Manichaeism, give a genealogical meaning in reference to the invocation of the Sun and Moon (Turk. kün ay). Confusingly, Zuev also compares Chigil to Persian čihil "forty".
Kamoliddin (2006) proposed that the ethnotoponym Chigil contains the morpheme -il (Turkic land, country). On the other hand, Alyılmaz (2017) etymologized Čigil as from plural and generalization suffix -GIl affixed onto tribal name Çik (OTrk. 𐰲𐰃𐰚:𐰉𐰆𐰑𐰣 Çik bodun), a people mentioned in Tang Huiyao as 赤 (MC: *t͡ɕhiᴇk̚) and, in Bilge Qaghan inscription, as allies of the Yenisei Kyrgyz and enemies of Latter Göktürks. Both the Chiks and the Shatuo are mentioned together, apparently as two distinct groups, in the same Tanghuiyao chapter,
However, Atwood (2010), in light of researches by Tenishev (1965) & Saguchi (1986), doubted the common scholarly identification of Chigils with Chuyue, from whom emerged the Shatuo as Chuyue is phonetically closer to Chunghyl, the name of a "bone" among the Yugurs in modern Gansu province.
As for *Čömül (Ar. Jumul جمل), H. W. Bailey derived it from Iranic *čamṛta < čam- "to stride out like a warrior", thus "warrior striders"
Hamilton (1962) and Zuev (2002) saw the first reference to the Chigil as 職乙 (Zhiyi), whose Middle Chinese pronunciation was reconstructed by Zuev as tšįək-iət, as a Tiele tribe mentioned in Book of Sui, compiled by Wei Zheng.