T’ai chu’u calendar

The T'ai-ch'u calendar was a significant development in ancient Chinese chronology. It was promulgated by Emperor Han Wu Ti in 104 BCE and established the civil year to begin with the lunation preceding the winter solstice, aligning with the Hsia calendar system. This lunar-solar calendar, known as yinyang li, aimed to synchronize the lunar month with the solar year by adding intercalary months. The system incorporated a 60-day cycle, combining 10 celestial stems and 12 terrestrial branches, a method used for over 3,000 years. The T'ai-ch'u calendar was used until the establishment of the People's Republic of China in 1949, when the Gregorian calendar was adopted.123