Chanyu
Chanyu or Shanyu, short for Chengli Gutu Chanyu, was the title used by the supreme rulers of Inner Asian nomads for eight centuries until superseded by the title "Khagan" in 402 AD. The title was most famously used by the ruling Luandi clan of the Xiongnu during the Qin dynasty and Han dynasty. It was later also used infrequently by the Chinese as a reference to Tujue leaders.
Etymology
According to the Book of Han, "the Xiongnu called the Heaven Chēnglí and they called a child gūtú. As for Chányú, it is a "vast great appearance".".L. Rogers and Edwin G. Pulleyblank argue that the title chanyu may be equivalent to the later attested title tarkhan, suggesting that the Chinese pronunciation was originally dān-ĥwāĥ, an approximation for *darxan. Linguist Alexander Vovin tentatively proposes a Yeniseian etymology for 撐犁孤塗單于, in Old Chinese pronunciation *treng-ri kwa-la dar-ɢwā, from four roots: **tɨŋgɨr- "heaven", *kwala- "son, child", *dar "lower reaches of the Yenisei" or "north", and *qʌ̄j ~ *χʌ̄j "prince"; as a whole "Son of Heaven, Ruler of the North".
Bailey derives from Proto-Iranian *tark- "to speak, command", from Proto-Indo-European *telkʷ-. He also compares a Saka title with the same semantic shift. Compare also Khotanese ttarkana and Ossetian tærxon.
Dybo derives from a Turkic root meaning "vast as the sky", and compares Old Uyghur *tarḳan- and tarḳar-. The Old Uyghur tarḳan- listed in her work is not found in Wilkens, and Caferoğlu glosses tarḳan- as "to feel embarrassed, to get tired of, to worry". tarḳar-, meanwhile, is glossed by both as "to expel, to distance oneself from something; to destroy, to expunge".