The clans who were given the title of Omi were powerful clans that were once in the position to stand on par with the royal family and occupied the highest position in the Yamato sovereign, including such clans as the Katsuragi clan, the Heguri clan, the Kose clan, the Kasuga clan, and the Soga clan (these clan names were the place names in Yamato (around Nara Basin).)
葛城氏（かつらぎ）、平群氏（へぐり）、巨勢氏（こせ）、春日氏（かすが）、蘇我氏（そが）のように、ヤマト（奈良盆地周辺）の地名を氏（ウヂ）の名とし、かつては王家と並ぶ立場にあり、大和王権においても最高の地位を占めた豪族である。