Many history books about the Jin dynasty began to disappear from the scene after the Tang-era Book of Jin was written in the Zhen'guan era (貞觀; 627–649) of the reign of Emperor Taizong of Tang and they became hard to find come the Song dynasty (960–1279).
Some of their contents are extant in the form of annotations found in Liu Yiqing's (劉義慶, 403–444) A New Account of the Tales of the World (Shishuo Xinyu; 世說新語), Pei Songzhi's annotations in Records of Three Kingdoms (c. 429), Xiao Tong's (蕭統) book Wen Xuan (文選: c. 520) and Li Fang's book Imperial Readings of the Taiping Era (太平御覽: c. 980).
In particular, Zang Rongxu's (臧榮緒: 415–488) Book of Jin and Wang Yin's (王隱) Book of Jin survived relatively intact to the present day.
As most of them were written during the Jin dynasty itself, it seems that they were incomplete and some of them were only of the Western Jin, though the Book of Jin by Zang Rongxu is thought to be more complete, since it recorded events from the time of Sima Yi, the first regent of Cao Wei from the Sima clan, to the fall of the Eastern Jin due to Liu Yu (劉裕: 363–422), and it consisted of 110 volumes.
Therefore, Book of Jin of Fang Xuanling (房玄齡: 579–648) is thought to have relied on Zang Rongxu's book.