In ancient times, the present-day Kameoka Basin was a large lake, and the region around the basin is said to have been named Ni-no-umi (cinnabar wave), or Tanba, after cinnabar waves rippling across the basin in a windy day; legend also has it that Okuninushi-no-mikoto, a famous deity in the Izumo Shinwa (Myths of Izumo), carved out a valley, poured water in it, reclaimed the area, and then named the river 'Hozu-gawa River' and the valley 'Hozu-kyo Gorge' after wife Deity, 'Mihotsu-hime,' and is the enshrined deity of the Izumo-Daijingu Shrine in Chitose-cho.
亀岡盆地は太古は大きな湖であり、風が吹くと美しい朱色の波が立ったところから、このあたりを丹のうみ・丹波と呼ぶようになったとされており、出雲神話で有名な大国主命が亀岡と嵐山の間にある渓谷を切り開いて水を流し土地を干拓して、切り開いた渓谷を「三穂津姫」の名前にちなみ保津川・保津峡と名付けたという伝説も残っており、出雲大神宮（千歳町）の祭神となっている。