Shoushi Calendar

Timeline

1. 1276–1280Astrological Bureau (Taishi Yuan) of Yuan Dadu · North ChinaAfter the fall of the Southern Song, Kublai Khan ordered a calendar reform. Wang Xun directed the calculations and Guo Shoujing the instruments and observations; gnomons were erected at Dengfeng in Henan and elsewhere for shadow measurements and observations across the realm, combining empirical measurement and mathematical methods to compile a draft of the new calendar.
2. 1280–1281Yuan Dadu · North ChinaThe calendar was completed in the seventeenth year of Zhiyuan and named the Shoushi Calendar; the following year it was officially promulgated throughout the realm, replacing older systems such as the Jin Daming Calendar and the Southern Song Huitian Calendar, and became the Yuan dynasty's unified official calendar.
3. 1281–1368Yuan dynasty realm · ChinaThe Shoushi Calendar served continuously as the official basis for calendrical computation throughout the Yuan dynasty, with the Astrological Bureau verifying solar terms and eclipses using instruments such as the abridged armilla and the tall gnomon. Its tropical year value matches that of the later Gregorian calendar, reflecting the peak of empirical calendrics in East Asia at the time.
4. 1368–1644Nanjing and Beijing · ChinaMing founder Zhu Yuanzhang renamed the calendar the Datong Calendar; its computational methods largely inherited the Shoushi Calendar, with only minor technical adjustments. This system was used until the late Ming, and after the early Qing adopted the Western Shixian Calendar, the Shoushi methods formally ceased to be used in official calendrics.