It was thought that after one thousand years of 'Shobo' (True Dharma) and one thousand years of 'Zobo' (Imitation Dharma), the age of Mappo (Final Dharma), the dark age when Buddhism perished, would begin.
正法の千年・像法の千年の後、仏教が滅びる暗黒時代、すなわち末法の世が始まったと考えられた。