This article investigates the regional variation of the Kazakh language spoken in the Bayan-Ölgii region of Mongolia, focusing on its lexical, phraseological, and word-formation characteristics. Drawing on data collected during a 2022 linguistic expedition, the study explores how historical, political, and educational conditions influenced the preservation and development of the Kazakh language outside Kazakhstan. The findings reveal that, despite several generations of separation, Mongolian Kazakhs have retained a high degree of linguistic identity. Their spoken and written Kazakh demonstrates distinctive features, including archaic vocabulary, synthetically derived word formations, and motivated phraseology. The study highlights the frequent use of lexical items and grammatical constructions that have either fallen out of use in Kazakhstan or evolved differently, as well as the presence of Mongolian loanwords. Special attention is paid to words created through synthetic processes, offering insight into regional creativity in lexical innovation. The research also documents sociolinguistic practices and communicative norms in the diaspora, noting more deliberate and respectful speech patterns compared to Kazakh speakers in Kazakhstan. These findings confirm the linguistic resilience of the Kazakh diaspora in Mongolia and underscore their contribution to maintaining and enriching the broader Kazakh linguistic heritage. This study concludes by emphasizing the need for continued monitoring and support to preserve the regional linguistic identity of Mongolian Kazakhs.