Abstract
The article presents the first historical and comparative study of auxiliary words (adverbs, auxiliary nouns, auxiliary verbs, modal words) in ancient Turkic runic inscriptions, comparing them with medieval and modern Turkic languages. It contributes to linguistics by analyzing these words through studies, statistical analysis, and theoretical justifications, with a focus on auxiliary verbs found in the Orkhon-Yenisei inscriptions. The research covers nine large and several small Orkhon-Yenisei inscriptions to identify and categorize the function words used in ancient Turkic. The study compares the auxiliary words in ancient Turkic with those in medieval and modern Turkic languages, revealing their morphological and phonetic similarities and differences. Additionally, differences between the eastern and western Hunnic Turkic languages are highlighted. The study finds that while the auxiliary word group is common in related Turkic languages, they belong to different categories, show variations in word formation, and have different names. A key result is that the auxiliary words in ancient Turkic runic inscriptions are substantively similar to those in medieval and modern Turkic languages. The primary language of the study is Kazakh, a closely related Turkic language. The article also discusses how some morphemes in Kazakh have lost their original meaning, leading to the formation of a new group of words with merged roots and morphemes, which are now categorized as auxiliary words.