koori had been established earlier than the demarcation of the ryoseikoku provinces and according to historical materials made of mokkan (narrow, long, and thin pieces of wood strung together that were used to write on in ancient times) such as "Hitachi no kuni fudoki" (the topography of Hitachi Province), provision of koori is thought to have been already completed nationwide in the reign of Emperor Kotoku.
評は、令制国の画定よりも早い時期に設置されており、『常陸国風土記』や木簡史料などから、孝徳期のうちに全国的に評の設置が完了したものと見られている。