This is the theory that Buddhism would decline, natural and man-made disasters would continue and the world would be plunged into chaos 2,000 years after Sakyamuni Buddha's passing into Nirvana (death).
釈尊の入滅（一般で言う「死去」）から2,000年目以降は、仏法がすたれ、天災人災が続き、世の中は乱れるとする思想である。