Abstract
The article presents a historical and grammatical comparison of the case systems of Old Uyghur and Kazakh. The study aims to identify the similarities and differences between the case systems of the two languages, reveal their language-specific features, and examine historical case forms that remain in active use in modern Kazakh. Foreign scholars specializing in Old Turkic languages note that the term “vibhakti,” one of the most frequently occurring grammatical terms in Old Uyghur, was used to denote the category of case. Previous studies also suggest that there are no substantial differences between the case systems of the two languages apart from certain variations in their case suffixes. The relevance of the study lies in the need to investigate the grammatical structure of Old Uyghur, which remains insufficiently explored in Kazakhstani scholarship, particularly the category of case, which attracted the attention of the Old Uyghurs themselves as early as the medieval period. Sentences extracted from “Sekiz Yükmek Yaruk,” one of the monuments of Old Uyghur writing, were used as the primary linguistic material. The study employed comparative, comparative-historical, classification, analytical, and translation methods. The findings provide a comparison of the case forms and their grammatical functions in Old Uyghur and Kazakh, explain the changes these forms underwent in the course of their historical development, and identify ancient case markers.