Beruni's Works: the Paleogeography of the Ustyurt Plateau and the Historical-Etymological Interpretation of the Term “Xiz Tangkizi”

This article examines the paleogeography of the Ustyurt Plateau and the historical-etymological interpretation of the term Xiz tangkizi based on the works of Abu Rayhan al-Biruni, primarily his Geodesy. Using historical-comparative, historical-geographical, linguistic, and paleogeographical methods, the study analyzes al-Biruni's descriptions of the ancient courses of the Amu Darya, the territories of Khwarazm, Jurjan, Sarykamysh, the Uzboy channel, and the Caspian basin. Particular attention is paid to the relationship between medieval geographical knowledge and modern paleogeographical evidence concerning the evolution of the Ustyurt Plateau. The article also reconsiders the etymology of the hydronym Xiz tangkizi. While previous scholars associated the term with the Turkic expression "Sea of the Maiden" or interpreted it as the "Red Sea," this study argues that the name may preserve an older hydronymic layer related to the ancient name of the Amu Darya—Oghuz (Greek: Oxus). Comparative analysis of medieval written sources, Turkic linguistic data, and regional toponymy suggests that phonetic development and folk etymology may have transformed the original hydronym into its later form. The findings demonstrate that al-Biruni's observations provide valuable evidence for reconstructing the historical hydrography, settlement patterns, and communication routes of the Ustyurt region. The study contributes to the historical geography of Central Asia by offering a new interpretation of one of the most debated geographical terms in al-Biruni's writings.