Of the Lotus-Nirvana period, the Nirvana Sūtra was expounded in one day and night while facing death. Śākyamuni Buddha passed away at the age of 80, but traditions also say that Śākyamuni was 79, 80, 81, 82, 105, or 120 years old when He died. The Sūtra of Clarification of the Age of Semblance Dharma, which foretells the decline of Buddhism during the Age of Semblance Dharma and advises the practice of almsgiving, was preached by the Hiraṇyavatī River just before the death of the Buddha. Thus, this sūtra is regarded to be the conclusion of the Nirvana Sūtra.

Ichidai Goji Keizu, Genealogical Chart of the Buddha’s Lifetime Teachings in Five Periods, Writings of Nichiren Shōnin, Doctrine 3, Page 244