I had a dream last night, in which I was holding forth to a group of admirers about the Turkic languages. I was just explaining that a native of Istanbul could, with some effort, be understood by Uyghur speakers of western China when someone in the group tried to tell us that in fact the "mountain people" of Japan could also understand Turkish. I retorted that I felt this was very unlikely.
In the cold light of day, I'm not actually sure what that dream heckler meant by "mountain people". I'm pretty sure I assumed they meant the Ainu, the aboriginal and ethnically distinct people of northern Japan. A swift look at Wikipedia suggests that there were 15 fluent speakers of Ainu left in 1996 and has no generally accepted relationship with other languages. Similarly Japanese and the Japonic languages of the Ryukyuan islands are generally held to be a language family isolate. So even in a dream it seems I'm right. Go me.