Ainu is a member of the small Ainu language family, which contains Kuril Ainu, Sakhalin Ainu, and Hokkaido Ainu. The family is sometimes regarded as language isolate, but many believe that it is a descendant of Neolithic languages. In the 1870s, Ainu was spoken in the northern islands, as well as the southern Sakhalin, of the Japanese archipelago. In 1875, the Japanese and Russian governments enacted the “Treaty for the Exchange of Sakhalin for the Kuril Islands,” which caused many of the Ainu living in Sakhalin to be displaced to Hokkaido. As epidemics increased in the region, most of the Ainu people were decimated. With the Japanese-Russian War, more displacement and oppression followed as the Japanese government favored traditional Japanese speakers, and fears arose that the Ainu (many of whom practiced Russian Orthodox Christianity), were spies for the Russian government. The Ainu culture was suppressed. Now, it is estimated that less than 10 people can fluently speak the language.