section_path: History/Solar calendars
section_name: Solar calendars
paragraph_text: Solar calendars
  
  The traditional Chinese lunisolar calendar was developed between 771 BCE and 476 BCE, during the Spring and Autumn period of the Eastern Zhou dynasty. Solar calendars were used before the Zhou dynasty period, along with the basic sexagenary system.
  
  One version of the solar calendar is the five-elements (or phases) calendar (五行曆; 五行历; wǔxíng lì), which derives from the Wu Xing. A 365-day year was divided into five phases of 72 days, with each phase preceded by an intercalary day associated with the claimed beginning of the following 72 day period of domination by the next Wu Xing element; thus, the five phases each begin with a governing-element day (行御), followed by a 72-day period characterized by the ruling element. Years began on a jiǎzǐ (甲子) day and a 72-day wood phase, followed by a bǐngzǐ (丙子) day and a 72-day fire phase; a wùzǐ (戊子) day and a 72-day earth phase; a gēngzǐ (庚子) day and a 72-day metal phase, and a rénzǐ (壬子) day followed by a water phase. Each phase consisted of two three-week months, making each year ten months long. Other days were tracked using the Yellow River Map (He Tu).
  
  Another version is a four-quarters calendar (四時八節曆; 四时八节历; sìshí bājié lì; ' four seasons eight solar terms calendar ', or 四分曆; 四分历; sìfēn lì; ' quarters calendar '). The weeks were ten days long, with one month consisting of three weeks. A year had 12 months, with a ten-day week intercalated in summer as needed to keep up with the tropical year. The 10 Heavenly Stems and 12 Earthly Branches were used to mark days.
  
  A third version is the balanced calendar (調曆; 调历; tiáo lì). A year was 365.25 days, and a month was 29.5 days. After every 16th month, a half-month was intercalated. According to oracle bone records, the Shang dynasty calendar (c. 1600 – c. 1046 BCE) was a balanced calendar with 12 to 14 months in a year; the month after the winter solstice was Zhēngyuè.
  
  A solar calendar called the Tung Shing, the Yellow Calendar or Imperial Calendar (both alluding to Yellow Emperor) continued to see use as an almanac and agricultural guide throughout Chinese history.