The Altai-Tarbagatai region occupied an important strategic and political position within the medieval Mongol world during the XIII–XIV centuries. This study investigates the historical geography of the region on the basis of the travel accounts of Giovanni da Pian del Carpine and William of Rubruck, combined with Kazakh historical traditions, toponymic evidence, and ethnographic data. Particular attention is devoted to identifying the possible locations of the palaces, hordes, and seasonal residences of the descendants of Genghis Khan, especially the domains of the Ogedei and Jochi dynasties in Eastern Saryarka, Altai, Tarbagatai, and the Irtysh basin. The article further analyzes the role of ancient communication networks, including caravan, military, and diplomatic routes such as the Bukhtarma road, which connected Central Asia, Siberia, and China. Comparative examination of medieval narratives with later Kazakh socio-political geography demonstrates the continuity of nomadic settlement systems and dynastic territorial traditions across centuries. The study concludes that the accounts of medieval travelers provide significant evidence for reconstructing the political landscape, migration patterns, and communication systems of the Mongol and post-Mongol era in East Kazakhstan.