"Sakuteiki" (a secret book on gardening) written during the Heian period contains detailed information about yarimizu (artificial stream in a garden) in addition to a pond, a mid island, a waterfall, a spring, and senzai (the trees and flowers in a garden), and it is natural for the gardens in Oshu (another name for Mutsu Province) in those days to have had a winding ditch in which Kyokusui no en could be held.
しかし、平安時代の造庭法秘伝書『作庭記』に、池・中島・滝・泉・前栽などに加えて遣水についても詳しく述べられているように、当時の奥州の庭園に曲水の宴を催すことのできる曲溝があるのは不自然ではない。