The O
mi clans generally took their names from the geographic location from which they originated, such as the , the , the , the , the , and the , thus making them regional chieftains in their own right. The most powerful
Omi added the prefix to the O
mi title, and were referred to as . Examples of
Ōomi mentioned in the
Nihon Shoki included during the reign of
Emperor Richū, during the reign of Emperors
Yūryaku and
Seinei, during the reign of
Emperor Keitai and the four generations of
Sogas who dominated the title during the 6th and 7th centuries:
Soga no Iname,
Soga no Umako,
Soga no Emishi and
Soga no Iruka. When the
kabane system was reformed into the
eight kabane system in 684 following a series of coup attempts, the powerful O
mi of the time were given the
kabane of
Ason, which ranked second under the new system, and O
mi itself was dropped to sixth in rank. == Name ==