This research is a narrative literature review that seeks to analyze comprehensively the factors that influenced Mongolian religion at the beginning of the twentieth century, including the Bogd Khanate, Pan Mongolism, and the political situation in outer Mongolia. The research questions and objectives are formulated with a review of extant literature on the topic and identification of research gaps. After the initial collection of 300 publications and the application of screening and inclusion/exclusion criteria, 102 publications are chosen for the study. The screening procedure is depicted using a PRISMA table, which comprehensively summarizes the final sample. In addition, search phrase combinations that delineate the various keywords used in the extensive literature search have been highlighted. Various underlying factors (e.g., cultural, political, economic, and social aspects) have substantially influenced Mongolian religion, particularly in the early twentieth century, according to the findings of this study. These factors are interconnected and significantly impact Mongolia's religious landscape. Overall, this study provides valuable insights into Mongolian religion's historical and developmental perspectives during a crucial period. In addition to providing a comprehensive analysis of the interrelationships between the Bogd Khanate and Pan Mongolism through the political prism of outer Mongolia, the present study sheds light on the complex dynamics that shaped Mongolian religion.