The Ainu language is the language of the Ainu people in northern Japan. It was not written until the 19th century. Since then, it has been written in katakana or the Latin alphabet.
In the 19th century, Ainu was spoken in Ezo (including Hokkaidō Island and the southern part of Chishima Islands), the southern part of Karapto (Sakhalin) and the northern part of Chishima Islands (Kuril Islands). Now it is only spoken in Hokkaidō.
Ainu had many dialects, including Chitose, Saru, and Karapto. Now only the Hokkaidō dialect survives. The dialects were so different from one another that a speaker of one dialect could not understand a speaker of another dialect.
Historically, speakers of Ainu lived near speakers of Japanese and Itelmen (from Kamchatka). The Nivkh, which was spoken in the northern part of Sakhalin, is another isolated language.