Tsunetane CHIBA's family and Hirokazu KAZUSANOSUKE supported Yoritomo not because both of them were followers of the Minamoto clan as "Azuma Kagami" says, but because they wanted to resist the oppression by the Fujiwara clan of Shimousa and the Satake clan of Hitachi which were related to the Taira family by making Yoritomo their leader, and it was their last-ditch plan to retrieve their own domains which had been deprived.
千葉常胤の一族、そして上総介広常が頼朝に加担したのは、『吾妻鏡』にいうような、両氏が累代の源氏の郎等であったからではなく、平家と結んだ下総の藤原氏、そして常陸の佐竹氏の圧迫に対して、頼朝を担ぐことによってそれを押し返し、奪い取られた自領を復活する為の起死回生の掛けであった。