When Finland declared its independence in 1917, the isthmus (except for the territory roughly corresponding to present-day Vsevolozhsky District and some districts of Saint Petersburg) remained Finnish, part of the Viipuri province with its center in Viipuri, the fourth largest Finnish city. A considerable part of the remaining area populated by Ingrian Finns seceded from Bolshevist Russia as the Finland-backed Republic of North Ingria, but was reintegrated with Russia in the end of 1920 according to the conditions of the Treaty of Tartu. In 1928–1939 parts of the isthmus which belonged to Russia constituted the Kuivaisi National District with its center in Toksova, with Finnish as the official language, according to the policy of national delimitation in the Soviet Union. However, in 1936 the entire Finnish population of the parishes of Valkeasaari, Lempaala, Vuole and Miikkulainen along the Finnish border was deported by the Soviet government.