The district system began with the enacting of the Taiho Code in 701 but regional administration organization before this time also consisted of 'kori' which was written using a different character (評).
郡の制度は701年（大宝元）施行の大宝令に始まるが、それ以前の地方行政組織は「評」と書かれ、「コオリ」と称された。