The words; 'Shima Province, Shima County' was seen on mokkan discovered from the former site of Heijo-kyo, so it was assumed that Shima Province consisted of one province and one county at first.
平城京跡から発見された木簡に「志摩国志摩郡」の表記が見られ、当初は志摩国は一国一郡であったと推定される。