Various ancient Greek calendars began in most states of ancient Greece between autumn and winter except for the Attic calendar, which began in summer.
The Greeks, as early as the time of Homer, appear to have been familiar with the division of the year into the twelve lunar months but no intercalary month Embolimos or day is then mentioned, with twelve months of 354 days. Independent of the division of a month into days, it was divided into periods according to the increase and decrease of the moon. Each of the city-states in ancient Greece had their own calendar that was based on the cycle of the moon, but also the various religious festivals that occurred throughout the year.