evidence: Kuril Islands, archipelago in Sakhalin oblast (province), far-eastern Russia. The archipelago extends for 750 miles (1,200 km) from the southern tip of the Kamchatka Peninsula (Russia) to the northeastern corner of Hokkaido island (Japan) and separates the Sea of Okhotsk from the Pacific Ocean. The 56 islands cover 6,000 square miles (15,600 square km). [...] The Kurils were originally inhabited by the Ainu, and they were later settled by the Russians and Japanese, following several waves of exploration in the 17th and 18th centuries. In 1855 Japan and Russia concluded the Treaty of Shimoda, which gave control of the four southernmost islands to Japan and the remainder of the chain to Russia. In the Treaty of Saint Petersburg, signed by those two countries in 1875, Russia ceded possession of the Kurils to Japan in exchange for uncontested control of Sakhalin Island. In 1945, as part of the Yalta agreements (formalized in the 1951 Treaty of Peace with Japan), the islands were ceded to the Soviet Union, and the Japanese population was repatriated and replaced by Soviets. Japan still claims historical rights to the southernmost islands and has tried repeatedly to persuade the Soviet Union and, from 1991, Russia to return those islands to Japanese sovereignty.