The article examines the problem of horse theft by Kazakhs of Western Siberia in the mid-19th century in the context of the legal framework of the tsarist government. Particular attention is paid to the concepts of "horse theft" and "barymta" in modern historical science to identify the attitude of the tsarist government to horse theft by Kazakhs and the application of measures to suppress them. Within the framework of a number of national liberation movements in the first half of the 19th century, the lack of their own administration among the Kazakhs of the Tobyl and Tombin provinces led to an increase in traditional horse theft, which was supported by internal Kazakhs in order to prevent the resettlement of peasants to Siberian lands. The fight against horse theft took place in the 50-70s of the 19th century and had its own specifics in the regions where there were cases of Kazakhs on the Novoishim line converting to Christianity and becoming peasants in order to avoid eviction. In connection with such problems, the article, based on written data and historical research, identified the causes and consequences of the increase in horse theft by Kazakhs who migrated to the inner part of the Irtysh.