It is said that the reason the Nitta clan was selected instead of the Ashikaga clan was because the neighboring Imagawa clan was familiar with the family tree of the Ashikaga lineage as they were part of the distinguished Ashikaga family.
足利氏でなく新田氏を選んだのは、隣接する今川氏が足利一門の名門で、足利系統の系譜に精通していた事が原因といわれている。