The article introduces written and visual materials from the center for Oriental Manuscripts and Woodcuts of the Institute of Mongolian, Buddhist and Tibetan Studies of the SB RAS archival collections related to the 1930 expedition to the Evenks of Lower Tunguska. Ethnographers Poltoradnev P.G. and P.P. Khoroshikh from Irkutsk worked as the members of the expedition. In the personal archive of P.P. Khoroshikh a map-scheme of the route, field records about the material, ritual and everyday culture of the Evenks, drafts of articles on the results of the expedition, as well as photographs and drawings with explanations by the author were revealed. The narrative part of the travel diary is compiled in chronological order of visiting camps and localities, contains various details of a complex and long journey. For the first time, the text of travel notes “Under the Arctic circle” is published, compiled in chronological order of visiting camps and localities and revealing various details of a complex and long journey. The subject matter of the identified materials fully reflects both the tasks set for the expedition and the professional interests of the team members – this is an information about the settlement of families, the peculiarities of making homes (chums), boats, utensils, clothing, crafts, rituals, etc. The collected information is supplemented by numerous photos of the region's aborigines, objects and localities, as well as drawings and diagrams of the location of objects with dimensions, orientation to the cardinal directions, location relative to each other, Evenk names and translation into Russian. The authors have formulated the questions, the answers to which have not yet been found in the archive materials – about the future fate of the collected collections, about the actual distribution of the responsibilities in the expedition, about a small number of publications on its results.