Although there were no particular Buddhist scriptures that instructed in the four directional set of the Buddha, Shaka or Shakyamuni, Amida, Miroku (Maitreya) and Yakushi (Bhaisajyaguru), there were several examples similar to the ones listed, dating to ancient times.
釈迦、阿弥陀、弥勒、薬師という四仏の組み合わせは特定の経典に説かれるものではないが、この四仏の組み合わせによる造像は古代にはしばしば見られたものである。