The First Iran-Russia War (1218–1228 AH/1804–1813 CE) is one of the most important events in the political and military history of Iran during the Qajar era, the consequences of which, beyond the direct confrontation between the two states, profoundly affected the social, economic, and political structures of the border regions. In the meantime, the Shahsavan tribe, as one of the most important border tribes in northwest Iran, played a multidimensional and decisive role. This research, with an analytical and historical approach, examines the contexts for the formation of the role of the Shahsavan tribe and explains its military, political, social, and economic functions during the First Iran-Russia War. The research findings show that the coherent social structure, the economy based on animal husbandry and seasonal migration, accurate geographical knowledge, and historical experience in confronting foreign threats turned the Shahsavan into an efficient force in local defense and logistical support. At the same time, the active participation of this tribe in the war had important consequences such as weakening the economic foundations, decreasing the active population, increasing dependence on the central government, and redefining the political position of the tribal leaders. Although these developments strengthened the security and political role of the Shahsavan in the short term, in the long term they led to changes in the power relations between the state and the tribes and reduced the independence of the tribal structure. The main question of the research is how the First Iran-Russia War redefined the military, political, and social position of the Shahsavan tribe, and what long-term consequences did this redefinition have for the tribal structure and its relations with the Qajar government?