 The city subsequently became the administrative center of Irkutsk Oblast, after East Siberian Oblast was divided into Chita Oblast and Irkutsk Oblast.During the communist years, the industrialization of Irkutsk and Siberia in general was strongly encouraged.The large Irkutsk Reservoir was built on the Angara River between 1950 and 1959 in order to generate hydroelectric power and facilitate industrial development.