Established in the late Heian period by Ietada KAZANIN, the second son of FUJIWARA no Morozane, the family was named after the Kazanin palace (Higashi ichijo in) which Ietada inherited from his father, Morozane.
平安時代後期の藤原師実の次男花山院家忠に始まり、家名は家忠が父師実から譲り受けた邸宅花山院（東一条院）にちなむ。