To make exquisite bookmarks in Oracle Bone Inscriptions, it is recommended to write small seal script font. After Qin Shihuang unified the six countries, he implemented the policy of "all books are the same, and all cars are on the same track", and the unified measurement was in charge of Prime Minister Li Si. On the basis of the original seal script used by Qin, he simplified it and created a unified Chinese writing form. Popular from the Qin Dynasty to the end of the Western Han Dynasty (about 8 AD), it was gradually replaced by official script. But because of its beautiful font and long ancient rhyme, it has always been favored by calligraphers.