It is said that "Sakuteiki Gardening Book" was created at the end of the Heian period, judging by its content, which is why the theory of 'Four Gods = Mountain, river, road and lake' can only date back to the end of the Heian period.
『作庭記』はその内容から平安時代末期の作とされており、「四神＝山川道澤」説は平安時代末期までしか遡り得ないのが現状である。