The article analyzes the information of the Arab-Muslim historical-geographical literature of the 10th–13th centuries regarding the settlement of two groups of medieval Bashkirs, called “outer” and “inner”. This classification was introduced into Arab-Muslim literature by the Central Asian geographer Abu Zeid Ahmad Ibn Sahl al-Balkhi (between 850 and 934). The reason for its appearance were the reports about the existence of  groups representing different peoples, in particular the Bashkirs and the Bulgars, isolated from each other. This issue was fleetingly touched in the works of Russian and foreign scholars, but did not become a subject of a special study. On the one hand, this was hampered by the influence of the long-obsolete Ugric theory of the Bashkirs’ origin, and on the other hand, by the poor knowledge of the original sources and the lack of integrated approach to their interpretation. As the analysis of sources showed, in the 10th–11th centuries there were simultaneously two groups of Bashkirs – in the Southern Urals and in the Black sea coast. The appearance of the western group of Bashkirs in the southern Russian steppes is connected with the war between two coalitions of the Turkic tribes: the Pechenegs, the Bashkirs, the Yadjnis and the Naukerdes on the one hand, and the Oguzes, the Kimaks, the Karluks and the Khazars – on the other. The first ones were defeated and were forced to migrate from the steppes of the Aral sea region to the Black sea coast at the end of the 9th century. After a 150-year stay in the southern Russian steppes, the Pechenegs and Bashkirs were pushed aside by the next wave of Turkic nomads to the Balkans and further to Hungary. Therefore, the classical school of Arab-Muslim geography, represented by such authors of the 10th century as al-Istakhri and Ibn Haukal, began to call the Western group of Bashkirs “inner” and the South Ural group – “outer”. Similarly, mentioned authors divided the Bulgars into the “inner” and the “outer” ones. The first ones corresponded to the Danube Bulgars, and the second – the Volga ones. This classification was based on the so-called “geographical egocentrism”, according to which close objects were designated as “inner”, and distant as “outer” ones. The 12th-century Arab geographer al-Idrisi extended this classification of peoples, arbitrarily transferring it to the Kumans, Russians and Armenians. As he did not find the Black Sea Bashkirs in the ethnogeography of his time, he similarly transferred that classification to the South Ural Bashkirs. Thus, the division of ethnic groups into “outer” and “inner” ones in his work was only a tribute to the old tradition and did not reflect the real historical picture.