Official website of the All Japan Federation of Karafuto (全国樺太連盟). Karafuto Prefecture (樺太廳, Karafuto-chō, commonly known as South Sakhalin) was a prefecture of Japan located in Sakhalin from 1907 to 1949. Karafuto became a territory of the Empire of Japan in 1905 after the Russo-Japanese War when the Russian Empire in the Treaty of Portsmouth ceded the portion of Sakhalin south of 50°N. Karafuto was established in 1907 as an external territory until being designated an "Inner Land" in 1943. Ōtomari (Korsakov) was the capital of Karafuto from 1905 to 1908 and Toyohara (Yuzhno-Sakhalinsk) from 1908 to August 1945 when the Japanese administration ceased to function after the invasion of South Sakhalin by the Soviet Union after the Surrender of Japan in World War II. Karafuto Prefecture was de facto replaced with Sakhalin Oblast and existed de iure until it was formally abolished as a legal entity by Japan on 1 June 1949.