At the time in Japan positions as monks were granted by the nation; and since there were only 3 ordination halls for the national recognition of monks (Nara/Todai-ji Temple, Tsukushi/Kanzeon-ji Temple, and Shimotsuke/Yakushi-ji Temple), the Tendai Sect was not able to train monks on its own.
当時の日本では僧の地位は国家資格であり、国家公認の僧となるための儀式を行う「戒壇」は日本に3箇所（奈良・東大寺、筑紫・観世音寺、下野・薬師寺）しか存在しなかったため、天台宗が独自に僧の養成をすることはできなかったのである。