From March 6 to 14, 2024, D.B. Sundueva worked in the Regional Literature Department of the National Library and in the State Archive of the Republic of Buryatia (Ulan-Ude). She reviewed contemporary Mongolian sources that address the theme of Russian old-settlers in Mongolia. She analyzed records from the metric books of the Kyakhtinskaya Voskresenskaya Church for the years 1914–1917 and 1919–1922 (File 177, case numbers 418–427), the Sharagolskaya Innokentievskaya Church for the years 1919–1922 (File 288, case numbers 41 and 42), and the Trinity Cathedral of Troitskosavsk for the years 1919–1921 (File 509, case numbers 45–47).

Preliminary analysis of the archival documents suggests that Russian residents of the Mongolian borderlands in the first quarter of the 20th century (prior to the closure of the Russian-Mongolian border) sought spiritual guidance and support from Orthodox parishes in Russia.