The work of Mahmud Kashgari 'Divan Lugat At-Turk' ('Dictionary of Turkic Dialects') is not just a dictionary in the modern sense of the word. This work concentrates the scientific achievements of philology, linguistics, history, geography, philosophy, and the problems of natural sciences. His lifetime fell in the 11th century. The scholar was originally from the southern shore of Issyk-Kul (Barskhan). At some point in his life, he moved from Barskhan to Kashgar and created his works under the name of Mahmud Kashgari. He received an excellent Arabic philological education in recognized centers of science and culture in the East: Kashgar, Bukhara, Samarkand, Nishapur, and Baghdad. Mahmud was well-versed in the Arabic language, was knowledgeable about the lives of many Turkic-speaking peoples, and wrote about them not from book sources. Regarding this, the author himself of the 'Dictionary of Turkic Dialects' wrote: "Although I come from the Turks, who speak the purest language, who occupy the foremost place by origin and lineage, I traveled through all the settlements and steppes of the Turks, step by step. I fully captured in my mind the living rhymed speech of the Turks, Turkmens, Oghuz, Chigils, Yagma, and Kyrgyz. And this book, after such a long study and search, I wrote in the most elegant manner, in the clearest language."
The Dictionary of Mahmud Kashgari represents a medieval encyclopedia of the life of Turkic peoples in the fullest sense of the word. Currently, 'Divan Lugat At-Turk' is the only source of information about the life of the Turks in the 11th century. It serves as an important source for studying the history of early medieval Turkic peoples living in Central and Central Asia. Thanks to it, we gain insight into the subjects of their material culture, the realities of everyday life, ethnonyms and toponyms, tribal divisions, kinship terms, titles and names of various officials, names of food and drink, plants, domestic and wild animals and birds, terms of animal husbandry, astronomy, the folk calendar, names of diseases and medicines, names of heroes, children's games and amusements, etc.
Of great interest are his round map of the world and information about the social structure of society, the main and secondary branches of economic life, and the cultural achievements of the Turks, including the Kyrgyz, Kazakhs, Uyghurs, Karakalpaks, Turkmens, Uzbeks, and Altaians. Undoubtedly, Mahmud Kashgari's dictionary holds great significance not only as a philological and historical source but also as a collection of the socio-philosophical thought of the Turkic peoples, capturing information about ethical norms of behavior, specific worldviews, and original judgments developed by them in the 10th-12th centuries. In other words, by studying the vocabulary of medieval Turkic peoples and their lexicon, Kashgari reflected the level of thinking of the people of his time.
Among the ethical views of Mahmud Kashgari, it is important to highlight concepts such as "labor," "friendship," and "reason." In them, he saw the guarantee, the foundation of human moral perfection. Mahmud viewed moral vices from the perspective of criticism and condemnation.