section_path: History/Lunisolar calendars by dynasty/Competing Warring states calendars
section_name: Competing Warring states calendars
paragraph_text: Competing Warring states calendars
  
  Several competing lunisolar calendars were introduced as Zhou devolved into the Warring States, especially by states fighting Zhou control during the Warring States period (perhaps 475 BCE - 221 BCE).From the Warring States period (ending in 221 BCE), six especially significant calendar systems are known to have begun to be developed. Later on, during their future course in history, the modern names for the ancient six calendars were also developed: Huangdi, Yin, Zhou, Xia, Zhuanxu, and Lu.
  
  Modern historical knowledge and records are limited for the earlier calendars. These calendars are known as the six ancient calendars (古六曆; 古六历), or quarter-remainder calendars, (四分曆; 四分历; sìfēnlì), since all calculate a year as 365 + 1 ⁄ 4 days long. Months begin on the day of the new moon, and a year has 12 or 13 months. Intercalary months (a 13th month) are added to the end of the year.
  
  The state of Lu issued its own Lu calendar (魯曆; 鲁历).
  
  The state of Jin issued the Xia calendar (夏曆; 夏历) with a year beginning on the day of the new moon nearest the March equinox.
  
  The state of Qin issued the Zhuanxu calendar (顓頊曆; 颛顼历), with a year beginning on the day of the new moon nearest the winter solstice. The Qiang and Dai calendars are modern versions of the Zhuanxu calendar, used by highland peoples.
  
  The Song state 's Yin calendar (殷曆; 殷历) began its year on the day of the new moon after the winter solstice.