Snakes in Chinese mythology of the Han dynasty, which claimed to rule with the protection of water and the north. Although the Black Warrior (Xuan Wu) is generally depicted as a snake entwining around a turtle, sometimes they are viewed as two separable generals. In Chinese culture mythologized snakes and snakelike beings have various roles, including the calendar system, poetry, and literature. In Chinese culture, years of the Snake are sixth in the cycle, following the Dragon Years, and recur every twelfth year. The Chinese New Year does not fall on a specific date, so it is essential to check the calendar to find
Calendar lunar phase cycle. Because the length of the lunar month is not an even fraction of the length of the tropical year, a purely lunar calendar quickly drifts against the seasons, which do not vary much near the equator. It does, however, stay constant with respect to other phenomena, notably tides. An example is the Islamic calendar. Alexander Marshack, in a controversial reading, believed that marks on a bone baton (c. 25,000 BC) represented a lunar calendar. Other marked bones may also represent lunar calendars. Similarly, Michael Rappenglueck believes that marks on a 15,000-year-old cave painting represent a lunar calendar.