The ecological environment of the Tibetan Plateau, known as the “Third Pole of the Earth”, is extremely sensitive and fragile. With rapid societal development, environmental problems on the Tibetan Plateau have become prominent, as it is downwind of the emission sources from densely populated areas in the Middle East and South Asia, and the plateau has become one of the regions significantly affected by transboundary pollutant transmission (including black carbon, BC). The Tibetan Plateau has a long history of life and religious sacrifices, including aromatic plant-burning, which were recorded in the geologic record; therefore, BC can be used as a potential indicator to study the changes in religious activities. In this study, BC analysis was carried out based on the plausible dating framework tested by the AMS 14 C and 137 Cs methods on successive sediment cores from Lake Dalzong, an alpine lake in the Gannan Tibetan Autonomous Prefecture, northeast of the Tibetan Plateau. It was found that the BC in the lake sediments mainly accumulated through proximity wet deposition, and its content changes reflected the prevalence of surrounding religious activities. The study results indicate that the area of Lake Dalzong has experienced three periods of enhanced religious activities in the last millennium: 1490–1565 CE (mid-Ming Dynasty), 1810–1890 CE (late Qing Dynasty), and 1920 CE to the present (since the founding of the Republic of China), and the increase in religious activities on this centennial time scale is a response to concurrent social development. This study is the first to extract information on the variation in religious activities from lake sediments on the Tibetan Plateau, which will help advance the study of the historical context of the Anthropocene on the Tibetan Plateau.