What's the difference between the first four histories and the last twenty?
The first four historical books: Historical Records (Sima Qian in the Western Han Dynasty), Historical Records (Ban Gu in the Eastern Han Dynasty), Historical Records of the Later Han Dynasty (Southern Song Dynasty) and History of the Three Kingdoms (Jin Dynasty) were all compiled privately. The History of the Three Kingdoms was written earlier than the Book of the Later Han Dynasty. These four histories were written by the author with all his life's energy. Historical Records, Hanshu and later Hanshu were not completed before the death of the main author. Historical Records was supplemented by Chu, Hanshu was supplemented by Ban Zhao and Ma Xubu, and the records of the Later Hanshu were taken from Sima Biao's continuation of Hanshu. Most of the later history books were edited by officials. Although there are many authors, the editing time is only a few years.