The Miura clan had been a powerful family in Sagami, fighting for MINAMOTO no Yoritomo and becoming extremely powerful retainers of the early Kamukura Shogunate but the direct line had been overthrown by the Hojo clan in the Battle of Hoji.
三浦氏は相模国の名族で源頼朝の挙兵に参じ、鎌倉幕府創立の功臣として大きな勢力を有していたが、嫡流は執権の北条氏に宝治合戦で滅ぼされている。