By the establishment of the Kamakura bakufu (Japanese feudal government headed by shogun), in most cases samurai in Togoku (the eastern part of Japan, particularly Kanto region) became gokenin (an immediate vassal of the shogunate in the Kamakura and Muromachi through Edo periods) to serve Kamakura bakufu and were appointed jito with their rights to rule their shoryo (territory) guaranteed by Kamakura bakufu.
鎌倉幕府の成立に従い、主に東国の武士は鎌倉幕府に奉公する、御家人となり地頭に補任され、所領の支配権が鎌倉幕府に保証された。