The area "behind the mountains" to the east, difficult to traverse, was left largely to the aborigines, three of whose seven main eastern tribes still inhabit the mountains around Hualien: the T'aiya, Punung and Amei peoples.
換句話說，這時的東台灣，只有原住山胞散居，全無漢民。「山後群番」囊括了七大族群，至於位居大山中段的花蓮，就以泰雅、布農、阿美三族為主。