The Power of Pure Land Buddhism and Amitabha Buddha, which introduced the concept of parallel worlds
Pure Land Buddhism (Honen, Jodo-shu, Shinran, Jodo Shinshu), which introduced the concept of a parallel world (Buddhist land) to existing Mahayana Buddhism (Hannya Sutra, Lotus Sutra) and the power of Amida Buddha (Muryotsu Sutra, Kanmyoju Sutra, Amida Sutra)