In the mid-Heian period, from the late 10th century to the 11th century, farmland development and their privatization by Tato, local powerful farmers, had been accelerated.
平安時代中葉の10世紀後期から11世紀の頃、地方の有力農民である田堵（たと）による田地開発とその私有地化が活発化した。