There are five chronologies. The chronological method is a commemorative method adopted in China today, and it is also a universal method in the world. Chronology of trunk and branch: Chronology of trunk and branch is one of the most basic chronologies in ancient China. The earliest record can be found in the astronomical training of Huainanzi, but this method was not popular in the Western Han Dynasty. In 54 AD, the main branch was officially used for chronology since the 30th year of Jianwu, Emperor Guangwu of the Eastern Han Dynasty. Chronology of branches and branches is widely used in ancient Chinese medicine books.

Chronological summary

Chronology refers to accurately recording the time of historical phenomena in words. China has a long history, which has been recorded in writing since Shang Dynasty, but it was not recorded until the middle of Western Zhou Dynasty. According to the information left by predecessors, Sima Qian clearly recorded the major historical events in the first year of the Western Zhou Dynasty and thereafter in Historical Records. The first year of the Republic is 84 BC1year. From this year on, the history of our country began to have an exact date.