Of the several theories that have been proposed about when the Kamakura bakufu was established, the one that emphasizes the importance of the creation of the positions of jito (land steward) and shugo (provincial military governor) as an epoch-making development showing the nationwide establishment of the Kamakura bakufu rule is supported by the majority of scholars in Japan.
なお、鎌倉幕府の成立時期にはいくつかの説が提出されているが、そのうち、地頭・守護の設置は幕府の支配権が全国的な広がりを持つに至った非常に重要な画期であるとして、学界では最も多くの支持を集めている。