Egypt and Mesopotamia. Bronze Age city states. Governed by kings (priest kings). Ugarit cuneiform texts suggest that kingship similar to Mesopotamian.
Among primitive tribes – calendar regulation = moon. Basic unit = month > complete lunation divided into 2 or 3 parts (lunar phases). Lunar synodic month = 29.53 days. Approximately 11 days different from solar year. Solar astronomical = 365.24 days = seasonal cycle.
Agricultural development > need to co-ordinate lunar and solar years. Problem solved – 2 ways. Thus (1) – lunar calendar – supplemented time to time by adding 13th month = solar year co=ordination = lunisolar calendar. Thus (20 – lunar basis abandoned. Months retained but extended/adapted. Period > correspondence – 365.24 cycle = solar calendar.
Egyptians – invented solar calendar – 3rd millennium. Divided year – 3 seasons + 12 months (30 days). Plus 5 additional days (beginning). Fixed by rising of Sirius in July.
Solar calendar = civil administration. Religious festivals = old lunar calendar > fell behind solar 11 days each year. Solution = lunisolar calendar (2500 BC) = intercalation (13th month) in 9 years out of 25 years. 25 year cycle. Thus – (25 x 365) = (16 x 354.36) + (9 x 383.89) = 9125. 13 x 29.53 = 385.89.
Mesopotamia – remained lunar – without systemic intercalation (until 5th century). Lunisolar calendar > constructed by the intercalation of 13th month. Every 7 years in 19. This = 19 year cycle. Explained by the autonomy of Mesopotamian city states. Thus (19 x 365.24) = (12 x 354.36) + (7 x 383.89) = 6939.5).
Greece – also independent regulation of calendar by each state. But – structure same everywhere. Year = 12 months (alternating 29/30 days). Eleven day deficit = intercalation (13th month) in 3 out of 8 years = Octennial Cycle (Octennium). Thus – (8 x 365) = (8 x 354) + (2 x 29) + 30 = 2920. Also lunar phases – not coincidental with days of calendar month to which assigned. Distinction made = actual and nominal new moon.
Greek Calendar – ultimate origin. Numerous correspondences – Greek/Babylonian festivals. two calendars = common basis? Babylonian offerings to dead = month of Teshrit. Teshrit = first of 2nd half year (Sept/Oct).
Greek = Athens – Genesis (feast of ancestors) = corresponding month – Becdromion. Similarly – Babylonian Kislev (Nov/Dec) – drink offerings to Ereshkigal. Fructifies earth. Ereshkigal = goddess of underworld. Attic Haloa = agrarian feast of Demeter = month of Poseidon (Dec/Jan).