Originally, all Turkic tribes that were part of the Turkic dynastic mythological system (for example, Uigurs, Karluks,
Ethans and a number of other tribes) were designated "Turkmens". Only later did this word come to refer to a specific ethnonym. The term derives from Türk plus the Sogdian affix of similarity -myn, -men, and means "resembling a Türk" or "co-Türk". A prominent Turkic scholar, Mahmud Kashgari, also mentions the etymology Türk manand (like Turks). The language and ethnicity of the Turkmen were much influenced by their migration to the west. Kashgari calls the Karluks Turkmen as well, but the first time the etymology Turkmen was used was by Makdisi in the second half of the 10th century AD. Like Kashgari, he wrote that the Karluks and Oghuz Turks were called Turkmen. Some modern scholars have proposed that the element -man/-men acts as an intensifier, and have translated the word as "pure Turk" or "most Turk-like of the Turks". Among Muslim chroniclers such as Ibn Kathir, the etymology was attributed to the mass conversion of two hundred thousand households in 971 AD, causing them to be named Turk Iman, which is a combination of "Turk" and "Iman" إيمان (faith, belief), meaning "believing Turks", with the term later dropping the hard-to-pronounce hamza.
Historically, all of the Western or Oghuz Turks have been called Türkmen or Turkoman; however, today the terms are usually restricted to two Turkic groups: the Turkmen people of Turkmenistan and adjacent parts of Central Asia, and the Turkomans of Iraq and Syria.
The modern Turkmen people descend, at least in part, from the Oghuz Turks of Transoxiana, the western portion of Turkestan, a region that largely corresponds to much of Central Asia as far east as Xinjiang. Oghuz tribes had moved westward from the Altay mountains in the 7th century AD, through the Siberian steppes, and settled in this region. They also penetrated as far west as the Volga basin and the Balkans. These early Turkmens are believed to have mixed with native Sogdian peoples and lived as pastoral nomads until the Russian invasion of the 19th century.