The Shiba clan originally took its name from the area called Shiba-gun County (Shiba-gun, Iwate Prefecture) of Mutsu Province where Ieuji ASHIKAGA became a ruler.
斯波氏は、足利家氏が陸奥国の斯波郡（岩手県紫波郡）を所領としたことから斯波氏と称するのを始まりとする。