Judging from the style of the details, it can be guessed that the east pagoda was built at the end of the Nara period and that the west pagoda was from late Nara period to the beginning of the Heian period.
細部の様式等から、東塔は奈良時代末期、西塔はやや遅れて奈良時代最末期から平安時代初頭の建築と推定される。