Although the date is unknown, at some point the north-west area separated off as Tajima Province, and after that, five districts in north separated as Tango Province on April 3, 713, establishing boundaries that would last long after.
年号不明であるが北西部を但馬国、その後、和銅6年（713年）4月3日に北部5郡を丹後国として分離し、後世まで長く続く領域が定まった。