This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Near the start of the Lotus Sutra, a question hangs in the air. If there is really only one vehicle, one final teaching that leads every being to buddhahood, why did the Buddha spend decades teaching several different paths instead of simply saying so from the beginning? The sutra's own answer is the five corruptions of the kalpa: the age itself is corrupted by war, famine and plague; views are corrupted by false doctrine; passions are corrupted by intensified greed and anger; beings themselves are corrupted, declining in virtue and capacity; and lifespan is corrupted, shortening from a mythic high point. Teaching the one vehicle directly to an audience already this compromised, the sutra suggests, would not have worked. Skillful means, provisional teachings pitched to what an audience can actually receive, were the honest response to a genuinely degraded age, not a concession or a lesser truth.
The five corruptions are not presented as a dated chronology the way this atlas's own Shobo, Zoho and Mappo entries are. There is no year attached to when the kalpa became corrupt, no countdown the way the three ages of the Dharma after the Buddha's death eventually acquired one. What the formula offers instead is a checklist: five marks by which an age can be recognized as fallen, available to be checked against at any point in Buddhist history rather than tied to a single reckoning. That flexibility is exactly what let later traditions, centuries after the Lotus Sutra reached China through Kumarajiva's translation, pick the formula up and use it for a new purpose.
This atlas records the doctrine's own scriptural basis and its five named parts under its doctrine entry. What that entry does not fully carry is the specific use East Asian Pure Land teachers made of it once the three age scheme gave decline a calendar. That connection is the subject of the companion article filed alongside this one.