Chinese New Year Snake. Many online Chinese Sign calculators do not account for the non-alignment of the two calendars, using Gregorian-calendar years rather than official Chinese New Year dates. One scheme of continuously numbered Chinese-calendar years assigns 4709 to the year beginning, 2011, but this is not universally accepted; the calendar is traditionally cyclical, not continuously numbered. Although the Chinese calendar traditionally does not use continuously numbered years, outside China its years are sometimes numbered from the purported reign of the mythical Yellow Emperor in the 3rd millennium BCE. But at least three different years numbered 1 are now used by various scholars,
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.