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Reference Articles 
Timeline (Adoption of the Gregorian calendar) 
Japanese calendar
Since the adoption of the Gregorian calendar, three different systems for counting years have been used in Japan: The imperial year (皇紀, koki) based on the mythical founding of Japan by Emperor Jimmu in 660 BC. The Japanese era name (年号, nengo) based on the reign of the current emperor, the year 2011 being Heisei 23 The European Anno Domini (Common Era) (西暦, seireki) designation Of these three, the last two are still in current use. The imperial calendar was used from 1873 to the end of World War II.
Iranian calendar
The Jalali (Jalaali) calendar is often called the Iranian calendar.