Turks first appeared as mixture of Indo-European - Steppe people and East Eurasians. But a lot of people like to call Turks full Mongoloids that assimilated Indo-European people. It is wrong. How when they have paternally y-dna of Western Eurasian-Steppe people they can be assimilated ? They were living in the Eurasian Steppe together and wanted to form united ethnicity. Even Proto-Turks-Huns were mixed. Turkic people always had tribal confedarations that included Western Eurasian and Eastern Eurasians. All of them had nomadic culture.
The term "Turk" first appeared in 552 A.D., when the tribe of the "Türük" founded its tribal federation, which is now known as the "Empire of the Kök Turks". The empire of the Kök-Turks existed from 552 to 744 as a union of nomadic tribes. The settlement area of the oldest people known as Turks was in eastern Central Asia, in an area that stretched from the Altai Mountains to Tianshan in the west and from Lake Baikal in the north to Altun in the south. After the fall of the Kök-Turkish Empire (745), various Turkic successor empires were founded on its territory. In the course of the dissolution of the empire, various tribes migrated westwards - among the most important are the Khazars, who established a state on the Sea of Azov. The migrations from the empire of the Kök Turks led to the foundation of various empires such as those of the Qarakhanids, Seljuks or Ottomans. They also led Turkic-speaking groups to the Middle East and Anatolia.