This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
The Lotus Sutra's five corruptions describe a condition, not a date. East Asian Buddhism's own three age scheme, Shobo, Zoho and Mappo, is the opposite: it is entirely a matter of dates, a thousand years of the true Dharma, a thousand years of the semblance Dharma, and then an unbounded final age in which only the words of the teaching survive. Put the two together and something useful happens. The three age scheme tells a practitioner what year they are living in, cosmically speaking. The five corruptions tell them how to check that the scheme is right, by looking at the world around them.
This is exactly the move Pure Land teachers in China and Japan made. Shandao, writing in seventh century China, and later Honen and Shinran in Japan, pointed to war, moral confusion, shortened attention and the general condition of the age as visible confirmation that Mappo had truly arrived and that the self-effort practices suited to an earlier age were no longer realistic. The argument runs in both directions at once: the three age scheme predicts that an age this bad should exist by now, and the five corruptions supply the description that lets a believer recognize their own age as the one predicted. Nattier's study of Buddhist decline literature treats this pairing as characteristic of how decline narratives work generally, a dated structure giving a diagnostic checklist somewhere to point.
The result was not a change to the five corruptions themselves, which stayed exactly the fivefold list the Lotus Sutra names. What changed was their job. A rhetorical justification for the Buddha's use of provisional teachings became, centuries later and in a different literature, the evidentiary basis for an entire school's central claim about the age its own followers were living in.