Shakyamuni explained that after his passing, there will be three major periods, respectively, called the Former, Middle and Latter Days of the Law, during which his teachings will spread throughout the world

There are various explanations in the sutras and other records about the duration of the Former, Middle and Latter Days of the Law. In “The Selection of the Time,” Nichiren Daishonin writes:  

In the Sutra of the Great Assembly, the World-Honored One of Supreme Enlightenment specifies the three future ages for Bodhisattva Moon Storehouse (Gatsuzo). The Buddha states that after his passing, there will be five five-hundred-year periods. The first five-hundred-year period will be the age of enlightenment (gedatsu kengo). The second period will be the age of meditation (senjo kengo). Together, these two periods will comprise the thousand years [of the Former Day of the Law.] The third period will be the age of reading, reciting, and listening (doju tamon kengo). The fourth period will be the age of building temples and stupas (tazo toji kengo). These two periods will comprise the second thousand years [of the Middle Day of the Law.] The fifth five-hundred-year period will be an age of conflict (tojo kengo), when “people will dispute and fight over my teachings, and my pure Law will become lost.” (Gosho, p. 836) 

The Three Periods and the Five Five-hundred-year Periods

1. The Former Day of the Law

   1. The first five hundred years—the age of enlightenment

   2. The second five hundred years—the age of meditation

2. The Middle Day of the Law

   1. The third five hundred years—the age of reading, reciting, and listening

   2. The fourth five hundred years—the age of building temples and stupas

3. The Latter Day of the Law

   1. The fifth five hundred years—the age of conflict

The Former Day of the Law

The Former Day of the Law refers to the first thousand years following Shakyamuni’s passing, which is further comprised of two five-hundred-year periods, which are the age of enlightenment and the age of meditation, respectively. (Note: The word kengo, meaning “firmly established,” is appended to the Japanese names of the first four of the five five-hundred-year spans to indicate the predominant type of practice exercised during those periods.)

During the first five-hundred-year period, the age of enlightenment, Shakyamuni’s teachings were transmitted correctly because the people who lived during that era were predominantly pure in heart. As a result, people practiced Buddhism to gain the Buddha’s wisdom and enlightenment.

During the second five-hundred-year period, the age of meditation, people utilized Mahayana training to enter a state of profound meditation, quiet their minds and ponder questions in a logical fashion in an attempt to reach Buddhahood.

Because Buddhist practice during the Former Day of the Law was replete with Shakyamuni’s teachings, training and proof (enlightenment), and because people who sought the Buddha path were endowed with superior capacities born of the good roots that they had produced through Buddhist practice in past lives, people were able to reap the fruits of Buddhahood during this thousand-year period.

Shakyamuni established a lineage of twenty-four successors whose responsibility it was to guard and propagate his teachings during the Former Day of the Law. Mahakashyapa, Ananda and others restricted their efforts to the dissemination of the Hinayana teachings for about the first hundred years directly after Shakyamuni’s death. Thereafter, Ashvaghosha, Nagarjuna, Vasubandhu and others refuted the Hinayana teachings and promoted Mahayana doctrine instead.

Furthermore, under the patronage of Kings Ajatashatru, Ashoka, Kamishka and others, Buddhist scripture was compiled, codified and widely disseminated throughout India. 

The Buddha’s Twenty-four Successors

The following is a list of the twenty-four successors entrusted with the Buddha’s teachings and who carried on the Lamp of the Law.

1.       Mahakashyapa                                 13. Kapimala

2.       Ananda                                           14. Nagarjuna

3.       Madhyantika                                    15. Aryadeva

4.       Shanavasa                                       16. Rahulata

5.       Upagupta                                         17. Samghanandi

6.       Dhritaka                                          18. Samghayashas

7.       Mikkaka                                           19. Kumarata

8.       Buddhananda                                   20. Jayata

9.       Buddhamitra                                    21. Vasubandhu

10.     Parshva                                           22. Manorhita

11.     Punyayashas                                    23. Haklena

12.     Ashvagosha                                     24. Aryasimha

The Middle Day of the Law

The Middle Day of the Law refers to the thousand-year period following the thousand years of the Former Day of the Law. The Middle Day consisted of the third and fourth five-hundred-year periods, which were the age of reading, reciting, and listening, and the age of building temples and stupas, respectively.

By this time, the Buddha had already been dead for a thousand years, and the number of spurious Buddhists intent on using Buddhism for less than honorable purposes was rapidly increasing. Buddhism, as it was handed down by the Buddha, was in grave danger of being lost. Because of the machinations of these “false prophets,” Mahayana teachings were being overturned in favor of Hinayana doctrine, and true Mahayana teachings were being supplanted by provisional Mahayana doctrine. Buddhism was falling into a state of utter confusion.

During this age, the Buddha’s original teachings and practices hung on by the slenderest of threads. Fewer and fewer people were able to attain Buddhahood because while the outer forms of Buddhism still existed, their true substance was fading away. That is why this period is also called the Age of the Counterfeit Law.

During the third five-hundred-year period, the age of reading, reciting, and listening, Buddhist canon spread to China, where many priests, including Kumarajiva and Hsuan-tsang, produced Chinese translations of and commentaries on the sutras. China was becoming a hotbed of doctrinal research.

The fourth five-hundred-year period, the age of building temples and stupas, furthermore witnessed the construction of many temples, stupas (memorial towers) and statues/images of the Buddha. In other words, the dissemination of Buddhism manifested more in physical form than in spiritual awakening.

The Buddhist teachings that spread to China during this period were carefully integrated with pre-existing Taoist doctrine. Even so, doctrinal disputes became more and more prevalent among fellow Buddhists, which ultimately led to the formation of ten schools of Buddhist thought known as the three schools of the south and seven schools of the north. When the Great Teacher T’ien-t’ai finally appeared on the scene, he revealed the fallacies of each of the ten schools and paved the way for the widespread diffusion of the Lotus Sutra. However, sects based on provisional Mahayana teachings, including Zen and Shingon, later spread throughout China, overshadowing the Lotus Sutra and the teachings of T’ien-t’ai. This gradually led to the degeneration of Shakyamuni’s teachings in China.

It was during the age of building temples and stupas that Buddhism made its way to Japan, and in keeping with the words that describe this age, the Japanese produced a formidable number of temples and stupas in Kyoto and Nara. What became known as the six sects of Nara flourished in the city of Nara during this era, but when the Great Teacher Dengyo appeared during the Heian period, he soundly refuted the doctrines of all six sects and replaced them with the true teachings of the Lotus Sutra.

Nevertheless, exactly as Shakyamuni had predicted, with the advent of the Latter Day of the Law, his pure Law began to fade. The Japanese Tendai sect, which was based on the Lotus Sutra, suffered a steady decline, while the doctrines of such erroneous sects as Shingon found a new lease on life and spread throughout the nation.

The Six Sects of Nara (Nanto rokushu)

The six sects of Nara were the Sanron, Jojitsu, Hosso, Kusha, Ritsu, and Kegon sects. They were the six most influential Buddhist denominations in Japan during the Nara period.

The Japanese term for these sects, nanto rokushu, literally means, “six sects” (rokushu) “of the southern capital” (nanto). The word nanto, or southern capital, refers to Kyoto, the capital of Japan during the Heian period (Heian-kyo), and is used in contrast to the word hokuto, or “northern capital,” which referred to the city of Nara (Heijo-kyo).

The Latter Day of the Law

The age indicated by the Japanese term mappo refers to a final age when the Buddha’s Law would disappear. At this time, Shakyamuni’s teachings would lose their ability to lead people to enlightenment, people’s hearts would become increasingly corrupt and chaos within society would lead to endless disputes.

With the dawning of the Latter Day of the Law, people began to lose respect for the Buddha’s teachings out of their own arrogance and mistrust. Erroneous ideologies sprung up one after the other, and some people even ventured to steal the doctrines of the Lotus Sutra and claim them as their own inventions. Consequently, people’s thinking became confused, their lives became poisoned with the unhealthy passions of greed, anger and ignorance, and society in general was filled with chaos and constant quarrels. (Shakyamuni himself had predicted that the Latter Day would be an age of conflict.) Furthermore, natural disasters began to occur with such unnatural frequency that it appeared as though the world were coming to an end. The world was becoming hopelessly corrupt.

In the midst of this Latter Day societal dissolution, Shakyamuni’s pure Law gradually became totally ineffectual. It was also at this time, however, that Nichiren Daishonin introduced the Great Pure Law and Nam-Myoho-Renge-Kyo to eliminate Latter Day society’s darkness at its source.

In The Medicine King (Yakuo; twenty-third) chapter of the Lotus Sutra, Shakyamuni speaks about how this Great Pure Law must surely spread throughout the world during the Latter Day of the Law. He instructs: “After I have passed into extinction, in the last five hundred year period, you must spread it abroad widely throughout Jambudvipa and never allow it to be cut off…” (Hokekyo; p. 539; The Lotus Sutra, Watson, p. 288) Shakyamuni predicts that during the fifth and final five-hundred-year period, which coincides with the dawning of the Latter Day of the Law, Nam-Myoho-Renge-Kyo, the Lotus Sutra for the Latter Day, would be revealed as the Buddhism that would relieve the sufferings of all mankind. Shakyamuni further predicts that this Law will spread throughout the entire world (Jambudvipa) without pause, for all time. The Great Teacher T’ien-t’ai comments on Shakyamuni’s prophecy as follows. “In the last five hundred year period, we are to share the blessings of the Mystic Way far and wide.” The Great Teacher Dengyo also proclaims: “Because the Former and Middle Days of the Law have nearly come to a close and the Latter Day is at hand, now is the time for the one vehicle of the Lotus Sutra.” Dengyo announces in this passage that the Latter Day is the age when the Mystic Law must spread throughout the world. Bddhism in India