- (historical) An ancient Central Asian title used by various Turkic (i.e. Hunnic, Xiongnu, Khazar), Mongolic and Indo-European peoples (i.e. Scythian and Tokharian), especially in the medieval era, and prominent among the successors of the Mongol Empire.
- (historical) An emblem during the Mongol Empire denoting a man freed of all kind of civil services.
Uncertain; perhaps from Turkic tarxan (“a man who has not to pay taxes, freed of all kind of civil service”), Mongolic darxan (“blacksmith, sacred or celebrated; a man who is freed off all obligations to pay taxes”), Middle Korean tarku-/tarho- (“to heat (a piece of iron); to deal with”), or Indo-Iranian tarkāna (“judgment”). All have been suggested as possible sources.
Another possibility also includes a common Altaic root with a derivation from Mongolian tar, dar (“ironmaster, blacksmith; to disperse, divide up, spread”) via Middle Mongolian tara ("scattered") or tarxa- ("be scattered"), ultimately from Proto-Mongolic *tara-, *tarka- (“to disperse, scatter”), possibly from Proto-Altaic *t`ájri (“to scatter, disperse”). Mongol form is hardly borrowed from Turkic (the Old Turkic form is tar-, while modern Kypchak forms like tara-, tarqa- are most probably borrowed from Mongolian. The original Turkic derivative form is preserved as *dar- (“to go apart, scatter, spread; to branch, be forked; branch; claw; finger”), possibly rooted in Proto-Altaic *tā̀ro (“to stretch, spread”).
A possible common origin for Turkic tarxan, Mongolian darxan, and Middle Korean tarku-/tarho- is supposed, interpreting this as a proof for early contacts between Central Asia and the Korean peninsula rooted in an ancient period of Turkic or proto-Altaic smith-shamanism closely related to the shamanistic feature of a blacksmith which was originated from ancient Turkic or Proto-Altaic (see Darhan, a forging-god associated with metal, in Altaic mythology). It is also argued that Mongolian darxan is an ancient loan word from Turkic tarqan, and likely originated from the Xiongnu and Huns where it was associated with a title for nobility. The word was borrowed into many languages, including Armenian tʿarxan, Georgian t’arxani, Ossetian tærxon and Russian тархан. Turning to the etymology of tarqan, Räsänen (JSFOu L, 7.5) proposed that this word was borrowed from Sino-Korean 達官 (tar-kwan) "emeritus" (compare to Japanese: 達官 (Tatsu-kan), “group officer”), referring to Ramstedt's article (Ramstedt, 1935: 87). Turkologist András Róna-Tas also proposes a common derivative of one of the seven medieval Hungarian tribes: Tarján.
D. Theodoridis noted that since the beginning of the 1920's British researchers have developed the assertion that the word tarqan and the Etruscan personal name Tarquin (Tarquinius) could be attributed to one and the same etymon.