Buddhist sūtras suggest that as the world moved farther and farther away from the time of the historical Buddha, his teachings would be refracted through an increasingly flawed mode of understanding; people would grow ever more deluded and liberation would become harder to achieve. In East Asia, this decline was said to span three successive periods: the age of the True Dharma (shōbō), the age of the Semblance Dharma (zōbō), and the age of the Final Dharma (mappō). Although chronologies differed, a rough consensus in Japan held that the first two ages had lasted a thousand years each and that the Final Dharma age had begun in 1052.

From a scholarly perspective, mappō represents a discourse, not a historical reality. Buddhism in early medieval Japan was thriving: Buddhist institutions, learning, arts, and culture all flourished, and a wealth of new interpretations arose. Nonetheless, the idea that the age was in decline provided a ready explanation for political troubles and natural disasters; Buddhist teachers appropriated the idea of mappō in different ways to advance competing agendas. Some urged that because the times were degenerate, practitioners should be all the more conscientious in carrying out traditional Buddhist disciplines such as maintaining precepts, practicing meditation, and studying scriptures. Others, of whom Nichiren is one, drew on notions of mappō to legitimize innovations in Buddhist thought and practice.