The region where the Shimane Peninsula, Shinji-ko Lake, and Nakanoumi came together, is known to be where the Old Izumo Culture was created.In the "Izumo-no-kuni Fudoki," a legend passed on in this region, the mythology, highlighting the peoples' lives and nature in the area, shows how the backdrop proved enough context for this.With this backdrop, we can see that this region in Japan is notable for being one of the most distinct areas that went through a huge geological fluctuation during the Cenozoic Era.