[en] This research explores the contribution of the Delisle brothers –Joseph-Nicolas and Louis – to the geography, cartography, and the discovery of Eastern Siberia, the Bering passage, and the Pacific Arctic. Their contribution to the European geographic and cartographic sciences is inestimable; as well as for the Russian Empire. They created the first general map of Russia, made the first analytic description of the Russian geography (biogeographic, physical, and human), especially in the Caucasus, Siberia, and in the Far-Eastern Arctic territories including Alaska. Joseph-Nicolas Delisle created the first department of geography in Saint-Petersburg, an astronomic observatory, and supervised the researches of the next generation of famous French and Russian Academics in Astronomy and geography.