Inventions-calendar-Ruby

 There was 360 days calendar in Sumerian time. In Mesopotamia the solar year was divided into two seasons, the "summer," which included the barley harvests in the second half of May or in the beginning of June, and the "winter," which roughly corresponded to today's fall-winter. Three seasons and four seasons were counted in northerly countries, but in Mesopotamia the bipartition of the year seemed natural. As late as c. 1800 BC the prognoses for the welfare of the city of Mari, on the middle Euphrates, were taken for six months. The months began at the first visibility of the New Moon, and in the 8th century BC court astronomers still reported this important observation to the Assyrian kings. The names of the months differed from city to city, and within the same Sumerian city of Babylonia a month could have several names, derived from festivals, from tasks (e.g., sheep shearing) usually performed in the given month, and so on, according to local needs. On the other hand, as early as the 27th century BC, the Sumerians had used artificial time units in referring to the tenure of some high official--e.g., on N-day of the turn of office of PN, governor. The Sumerian administration also needed a time unit comprising the whole agricultural cycle; for example, from the delivery of new barley and the settling of pertinent accounts to the next crop. This financial year began about two months after barley cutting. For other purposes, a year began before or with the harvest. This fluctuating and discontinuous year was not precise enough for the meticulous accounting of Sumerian scribes, who by 2400 BC already used the schematic year of 30 12 = 360 days. 
 * __Sumerian 360 days Calendar __** 