The article is devoted to the systematization and description of toponyms associated with water bodies on the territory of the Middle Irtysh region, the origin of which may be associated with Indo-Iranian languages. Despite the controversial origin of the names of certain geographical names, their analysis contributes to solving problems not only in terms of studying the chronological layers of toponymy of Kazakhstan, but also in the context of studying the history and culture of the population that once lived here. It indicates the historical binding of toponyms that may be associated with native speakers of Indo-Iranian languages who, according to some researchers, lived in the designated area during the Bronze Age and Early Iron Age. Before the era of writing and cartography, orientation in deserted mountains was a problem, recognition of an object on the ground occurred by the oral name of the place, the name of which briefly and succinctly indicated one or two noticeable and distinctive features of the object and the surrounding area. Rivers (hydronyms) have the most stable names in time, as well as some tracts and notable mountains located near ancient communications, near historical places of residence and important in the life support and management of people. The names of villages often came from the names of rivers and from the geomorphological assessment of the settlement site, reflecting the space and terrain, taking into account the properties of the object and its degree of significance for people. Sometimes a toponym denoting a local object can expand its meaning, or the name is transferred to neighboring objects, usually the name of the river is transferred to the name of the gorge, but sometimes vice versa, the name. rivers are often transferred to the name. Toponyms appeared as man mastered the mountains, in the form of "toponymic corridors" corresponding to ancient pack trails, passes and valleys and hollows convenient for settling. The scientific novelty of the study consists in the analysis and interpretation of toponyms of Indo-Iranian origin associated with water bodies in the Middle Priirtysh region, based on materials from Pavlodar, East Kazakhstan and Abay regions. The study makes it possible to trace historical connections and the influence of Indo-Iranian peoples on the formation of the toponymic landscape of this territory, as well as to contribute to the understanding of the processes of migration and cultural exchange in the region. The methodological approach may include a comprehensive examination and comparison of different data sources, interdisciplinary analysis, use of the comparative method, etc. It is also important to consider the context of the study, the resources available and the objectives of the study to select the most appropriate methods and methodology. It is also important to consider the research context, available resources and research objectives in order to select the most appropriate methods and methodology.