Through the Treaty of Portsmouth, the portion of Sakhalin Island south of 50°N became a colony of Japanese Empireball in 1905. In 1907, the prefecture of Karafuto was established, with its capital at Ōtomari (now Korsakov) in 1905, and later Toyohara (now Yuzhno-Sakhalinsk) in 1907. In 1945, with the defeat of Japan in World War II, Karafuto was occupied by Soviet troops and its Japanese administration ceased to function. Karafuto Prefecture was formally abolished as a legal entity on June 1, 1949. Since 1951, the southern part of Sakhalin has been a part of Sakhalin Oblast in Russiaball.