The koden had been carried out immediately after Taika no Kaishin (the Taika Reforms); and as the handen-sei (Ritsuryo land-allotment system) was enforced, the koden was conducted before the handen, and kodencho (individual registers of the koden) were recorded.
校田は大化改新直後から行われ、班田制の施行とともに班田の前に校田が行われ、校田帳が作成された。