Sakishima comprises a group of islands situated between Okinawa and Taiwan, forming a culturally important bridge between Japan and Taiwan. Studies of the languages of the Ryukyuan islands are valuable for an accurate understanding of the linguistic history of Japan as a whole. This monograph is the first attempt – in any language – at a large-scale reconstruction of the three languages of the southern Ryukyus (Sakishima), viz., Miyako, Yaeyama andYonaguni. An introduction outlines a brief history of the area, with a concise linguistic history, followed by an explanation of the languages studied. Succeeding chapters are devoted to the reconstruction of each of the three proto-languages. The three proto-languages are then compared and proto-Sakishima is reconstructed. This monograph provides data illustrating the importance of the language of Sakishima in understanding the linguistic history of the larger language family of Japonic.