This font is called Xiao Zhuan, which is the famous "calligraphy with the same character" in history. Before Qin Shihuang unified the six countries, the characters of other countries were also very different. Even the same word can be written in several ways.
After Shang Dynasty, characters became popular. As an official language, bronze inscriptions are relatively consistent in form.
However, during the Spring and Autumn Period and the Warring States Period, there were regional differences in folk characters, such as weapons, Wen Tao, silk books and bamboo slips. This situation has hindered the economic and cultural exchanges between different places, and also affected the effective implementation of policies and decrees of the central government. So, after Qin unified the Central Plains, Qin Shihuang ordered Li Si and others to sort out the unified characters. Since then, more convenient calligraphy has been adopted and unified characters have been stipulated. In this way, cultural exchanges between different places are much more convenient. This is called "the same book". Here, "one" and "same" are synonymous, that is, "unity".