polymorphism study suggested that Eurasian Steppe slowly transitioned from Indo European and Iranian-speaking groups with largely western Eurasian ancestry to increasing East Asian ancestry with Turkic and Mongolian groups in the past 4000 years, including extensive Turkic migrations out of Mongolia and slow assimilation of local populations. Genetic data shows that the different Central Asian Turkic-speaking peoples have between 22% to 60% East Asian ancestry (samplified by "Baikal hunter-gatherer ancestry" shared with other Northeast Asians and Eastern Siberians), in contrast to Iranian-speaking Central Asians, specifically Tajiks, which display genetic continuity to Indo-Iranians of the Iron Age. Certain Turkic ethnic groups, specifically the Kazakhs, display even higher East Asian ancestry. This is explained by substantial Mongolian influence on the Kazakh genome, through significant admixture between medieval Turkic Kipchaks with medieval Mongolians. The data suggests that the Mongol invasion of Central Asia had lasting impacts onto the genetic makeup of Kazakhs. Early historical attestation The earliest separate Turkic peoples, such as the Gekun (鬲昆) and Xinli (薪犁), appeared on the peripheries of the late Xiongnu confederation about 200 BCE (contemporaneous with the Chinese Han Dynasty) and later among the Turkic-speaking Tiele as Hegu (紇骨) and Xue (薛). The Tiele (also known as Gaoche 高車, lit. "High Carts"), may be related to the Xiongnu and the Dingling. According to the Book of Wei, the Tiele people were the remnants of the Chidi (赤狄), the red Di people competing with the Jin in the Spring and Autumn period. Historically they were established after the 6th century BCE. The Tiele were first mentioned in Chinese literature from the 6th to 8th centuries. Some scholars (Haneda, Onogawa, Geng, etc.) proposed that Tiele, Dili, Dingling, Chile, Tele, & Tujue all transliterated underlying Türk; however, Golden proposed that Dili, Dingling, Chile, Tele, & Tiele transliterated Tegrek while Tujue transliterated Türküt, plural of Türk. The appellation Türük (Old Turkic: 𐱅𐰇𐰼𐰰) ~ Türk (OT: 𐱅𐰇𐰼𐰚) (whence Middle Chinese 突厥 *dwət-kuɑt > *tɦut-kyat > standard Chinese: Tūjué) was initially reserved exclusively for the Göktürks by Chinese, Tibetans, and even the Turkic-speaking Uyghurs. In contrast, medieval Muslim writers, including Turkic speakers like Ottoman historian Mustafa Âlî and explorer Evliya Çelebi as well as Timurid scientist Ulugh Beg, often viewed Inner Asian tribes, "as forming a single entity regardless of their linguistic affiliation" commonly used Turk as a generic name for Inner Asians (whether Turkic- or Mongolic-speaking). Only in modern era do modern