What is the earliest calendars

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 What is the earliest calendars .
         IntractinIn fact about the earliest calendar.

    The earliest calendars invented by man which were based on the motion of the moon , in this calendar a year was upto 12 lunar months , which were alternately 29 and 30 days long . there year was 11 day's short , so they added an extra month every 3 year . This calendar was not accurate over long periods . 
             The ancient Egyptian established a solar calendar based on the sun . they split their year of 365 days into 12 months of 30 days adding 5 days at the end of the year . 
    After that , the next calendar were came from the Roman,. These calendar was based on ancient Egyptian pattern . But they altered the number of days in months to eliminate the extra  5 days .

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