the Tatars were located west of the Ili river and west of the Bashkirs, whom Kashagari already located west of Tatars. Claus Schönig attributed such contradictions to errors made when the text and the map were copied. Kashgari additionally noted that Tatars were bilingual, speaking Turkic alongside their own languages; the same for the Yabaqus, Basmïls, and Chömüls. Yet available evidence suggested that the Yabaqus, Basmïls, and Chömüls were all Turkic speakers; therefore, Mehmet Fuat Köprülü concludes that in the 11th century, the Yabaqus, Basmïls, Chömüls, Qays and Tatars – the last two of whom Köprülü considers to be Turkified Mongols – could speak Kashgari's Karakhanid dialect as well as their own Turkic dialects, yet those peoples' own dialects differed from Karakhanid so substantially that Kashgari considered them other languages. According to Klyashtorny, the name "Tatar" was the Turkic designation for Mongols. As Ushnitsky writes, the ethnonym "Tatar" was used by the Turks only to designate "strangers", that is, peoples who did not speak Turkic languages. The Turkic tribes living among their Mongol-speaking neighbors were also called "tat" or "tat-ar". According to Bartold, the peoples of Mongolian origin who spoke the Mongolian language had always called themselves Tatars. Subsequently, this word was completely supplanted by the word "Mongol". History The Rourans, Tatars' putative ancestors, roamed modern-day Mongolia in summer and crossed the Gobi desert southwards in winter in search of pastures. Rourans founded their Khaganate in the 5th century, around 402 CE. Among the Rourans' subjects were the Ashina tribe, who overthrew their Rouran overlords in 552 and annihilated the Rourans in 555. One branch of the dispersed Rourans migrated to the Greater Khingan mountain range where they renamed themselves after Tantan, a historical Khagan, and gradually incorporated themselves into the Shiwei tribal complex and emerged as 大室韋 Da (Great) Shiwei. The Otuken region, constantly mentioned in the Orkhon inscriptions as the place of residence of the Turks, according to Mahmud Kashgar, was once in the country of the Tatars. According to Vasily Bartold, this message suggests that the Mongols already then reached the west to the area where their neighbors from different sides were Turkic tribes. Persian historian Gardizi listed Tatars as one of seven founding tribes of the Turkic Kimek confederation. The Shine Usu inscription mentioned that the Toquz Tatars, in alliance with the Sekiz-Oghuz, unsuccessfully revolted against Uyghur Khagan Bayanchur, who was consolidating power between 744 and