This paper examines the legacy of the 1896 Selenga Valley Expedition led by the French doctor Jean-Jacques Matignon on Russian research on bubonic plague in the decade preceding the great Manchurian plague epidemic of 1910-1911. With particular focus on Danilo Kirilovich Zabolotny’s expedition to Weichang (1898) and Ivan Stepanovich Dudchenko-Kolbashenko’s expedition to Mongolia and Transbaikalia (1907-1908), the paper will examine how Matignon’s hypothesis that plague was not endemic in the region but rather imported from South China on the back of so-called ‘coolies’was subsequently entwined with the Russian hypothesis of a zoonotic origin of plague, focused on Siberian marmots (tarbagan) as the endemic vector of the disease in Inner Asia...