Abstract
This article introduces little-known visual and written sources discovered during a 2024 research mission in the archives, museums, and libraries of the Abay, East Qazaqstan, and Pavlodar regions. The study's scientific novelty and significance are due to its interdisciplinary nature, which is carried out at the intersection of history, historical geography, and historical cartography. The identified visual sources clearly demonstrate the various designs of fortifications, fortification lines, border outposts, the routes and armaments of military units of the Russian Empire, as well as the history of administrative-territorial divisions. An analysis of the identified visual and written sources revealed that border formation was a long-term and multifaceted process. Key characteristics include the location of fortifications, militarization, deep territorial and military expansion into the Qazaq steppes, the presence of permanent military units, and paramilitary forms of governance. This study identifies several stages in the formation of the Qazaq border from the 18th to the 20th centuries: the construction of fortresses (to strengthen imperial power and influence over the Qazaqs), the creation of a network of fortresses (to push the Qazaqs deeper into the Steppe), the formation of a border zone, and the reform and fortification of the border. Borders were defined and fortified due to natural resources, rivers, and mountain ranges. This study of the "frontier" as a spatial phenomenon in the history of Qazaqstan from the 18th to the early 20th centuries is based on visual and written sources from museums, libraries, and archives in Ust-Kamenogorsk, Pavlodar, and Semey