Predictions of the decline of the Buddhist teaching had played an important role in Indian and Chinese Buddhism. In China these predictions had been crucial to the development of Pure Land Buddhism and the Sect of the Three Stages. Buddhists representing these movements had argued that a new age in Buddhist history required new teachings. Other Chinese monks, such as Daoxuan, had responded to the threat of a decline in Buddhism by calling upon monks to faithfully follow established Buddhist practices, especially those specified in the precepts.

In Japan the idea of a decline in Buddhist teachings and practices was familiar to Japanese monks as early as the Nara period. Particularly popular was a theory which classified the deterioration of Buddhism into three stages: the Period of the True Dharma (shōbō), the Period of the Imitated Dharma (zōhō) and the End of the Dharma (mappō).

Of the various theories concerning the length of these periods, two were particularly well-known in China and Japan. According to the first, the Period of the True Dharma lasted five-hundred years and the Period of the Imitated Dharma lasted one-thousand years. By the eighth century, the Chinese and Japanese usually dated the death of the Buddha as occurring in 949 BC,⁵ thus the Nara and Heian periods corresponded to mappō.

Note 5: During the Six Dynasties, Chinese Buddhists moved the date of the death of the Buddha back in time from the fifth century BC to 949 BC in order to counter Taoist charges that the arrival of Buddhism had caused Chinese dynasties to be short-lived and to prove that the Buddha had lived before Lao Tzu. Eventually the date of 949 BC was accepted as the date of the Buddha’s death by most Chinese. By claiming that Buddhism had arrived in China shortly after the Buddha’s death, Chinese monks could argue that Buddhism had been taught in China during the long Chou Dynasty and thus had not adversely affected the longevity of Chinese dynasties.