Changes

===Historical ''Nengō''===

===Historical ''Nengō''===

Prior to the convention that started with the Meiji Era, the start of a new era could be declared for any number of reasons. The main reasons for declaring a new era would be the first, fifth and 58^th years of the "sexagenary cycle" (十干十二支 ''jikkan jūnishi''), based on the [[Chinese]] system of 60 combinations of the two basic cycles, the ten calendar signs and the twelve signs of the Chinese zodiac, the ascension of a new Emperor to the throne, an auspicious event, or a natural disaster.

Prior to the convention that started with the Meiji Era, the start of a new era could be declared for any number of reasons. The main reasons for declaring a new era would be the first, fifth and 58^th years of the "sexagenary cycle" (十干十二支 ''jikkan jūnishi''), based on the [[Chinese]] system of 60 combinations of the two basic cycles, the ten calendar signs and the twelve signs of the [[Chinese zodiac]], the ascension of a new Emperor to the throne, an auspicious event, or a natural disaster.

Many periods were only three or four years long and the names had nothing to do with the Emperor of the time. Furthermore, a change of emperor did not necessarily mean an immediate change to a new era; this normally occurred between one to two years after the Emperor's death.<ref>Ryusaku Tsunoda, et. al., comp., Sources of Japanese Tradition, Columbia University Press, 1958</ref>

Many periods were only three or four years long and the names had nothing to do with the Emperor of the time. Furthermore, a change of emperor did not necessarily mean an immediate change to a new era; this normally occurred between one to two years after the Emperor's death.<ref>Ryusaku Tsunoda, et. al., comp., Sources of Japanese Tradition, Columbia University Press, 1958</ref>