The split of the Hongwan-ji Temple religious community into east and west originated from the difference of opinion within the community at the end of the Ikko Ikki (Ishiyama War) (1570-1580), which was fought around Ishiyama Hongwan-ji Temple at the end of the Age of Civil War.
本願寺教団の東西分派は、戦国時代の最末期、大坂の石山本願寺を本拠地として戦われた一向一揆（石山合戦）（1570年～1580年）終結時の教団内部における見解の相違に遠因を持つ。