今天随处可见的日历，雏形出现在几千年前

Group 1 - The article discusses the historical significance of calendars in China, highlighting their evolution from ancient times to the present [1][3]. - It mentions that the earliest known physical calendar was created during the Tang Dynasty, specifically in the year 805 AD, known as the imperial calendar [5]. - The article notes that the "Shoushi Calendar," developed by astronomer Guo Shoujing during the Yuan Dynasty, was a pinnacle of world calendars at the time, with an accuracy of only 26 seconds deviation from the actual solar year [5]. Group 2 - The article emphasizes the importance of calendars in recording significant events and daily activities, particularly in the context of the emperor's actions and state affairs [5]. - It highlights the transition from hand-copied calendars to printed versions during the late Tang Dynasty, which made calendars more accessible and popular among the general public [5]. - The influence of the "Shoushi Calendar" extended beyond China, as it was adopted and adapted by countries like Korea and Japan, becoming a common calendar in East Asia [5].