Masamitsu OTA moved to Shimotsuke Province around 1150 in the end of the Heian period and settled in Oyama shoen (manor in medieval Japan), calling himself Shiro OYAMA or Shimotsukenodaiten OYAMA to be the founder of the Oyama family.
太田政光は平安時代末期の1150年頃、下野国に移住して小山荘に住し、小山四郎、小山下野大椽と称し小山氏の祖となった。