However, the Mito family was based within kanhasshu (eight provinces which composed the Kanto region in the Edo period) and governed Hitachi Province, which had been recognized as a taikoku (the best ranked provinces) and Shinno-Ningoku (provinces whose official governors were the Imperial princes) in Engishiki (a set of ancient Japanese governmental regulations).
しかし、水戸家自体が関八州にあり、また治める常陸国は延喜式における大国かつ親王任国である。