In 1020, MINAMOTO no Morofusa, a child of the Imperial Prince Tomohira of the Emperor Murakami, was given the surname of MINAMOTO no Ason and MINAMOTO no Masazane, the grandchild of this prince, founded the family.
村上天皇の皇子具平親王の子源師房が寛仁4年（1020年）に源朝臣の姓を賜わり、その孫にあたる源雅実が祖。