Beishi 北史 "History of the North" is a one-book parallel to the the official dynastic histories ( 正史) of the Northern Wei dynasty 北魏 (386-534; Weishu 魏書), its two short-lived successor dynasties of the Northern Qi 北齊 (550-577; Beiqishu 北齊書) and (Northern) Zhou 北周 (557-581; Zhoushu 周書), and the Sui dynasty 隋 (581-618; Suishu 隋書). Correctly said it is an alternative history (bieshi 別史), but belongs nevertheless to the corpus of the dynastic histories because it was of great importance for the reconstruction of the individual dynastic histories.
It was written by Li Yanshou 李延壽 (fl. 659), who also compiled a parallel book to the histories of the Southern Dynasties 南朝 (420-589), the Nanshi 南史. The part covering the Northern Wei comprises 5 juan (ch. 1-5, including the emperors of the Eastern and Western Wei) of imperial annals-biographies (benji 本紀), that of the Qi 3 juan (6-8), that of the Zhou 2 juan (9-10), and that of the Sui 2 juan (11-12).
There are 88 juan of normal and collective biographies (liezhuan 列傳). The first chapter is headed by a preface written by the author (Zixu 自序). The time frame of the book ranges from 386, the year of the foundation of the Wei empire, until 618, when the Sui dynasty was overthrown by the Tang dynasty 唐 (618-907). The book was completed in 643. Some chapters are lost, like the biography of Emperor Yang 隋煬帝 (r. 604–617) that was later supplemented with that from the Suishu.
The collective biographies render the lives of imperial consorts (13-14 Houfei zhuan 后妃傳), their kinsmen (80 Waiqi zhuan 外戚傳), the imperial houses (15-19 [Beiwei], 51-52 [Beiqi], 57-58 [Beizhou], 71 [Sui]), Confucian scholars (81-82 Rulin zhuan 儒林傳), writers (83 Wenyuan zhuan 文苑傳), persons of filial conduct (84 Xiaoxing zhuan 孝行傳), persons of modest character (85 Jieyi zhuan 節義傳), benevolent officials (86 Xunli zhuan 循吏傳), cruel officials (87 Kuli zhuan 酷吏傳), scholars living in seclusion (88 Yinyi zhuan 隱逸傳), magicians and diviners (89-90 Yishu zhuan 藝術傳), outstanding women (91 Lienü zhuan 列女傳), minions (92 Enxing zhuan 恩幸傳), rulers of the Sixteen States 十六國 (300~430; 93 Zanwei zhuan 僭偽傳), and foreign countries and "barbarian" peoples (94-99). The last chapter (called "Postface", 100 Xuzhuan 序傳) is a biography of Li Gao 李暠, King Wuzhao of Liang 涼武昭王 (r. 400–417), who was seen as the ancestor of the Tang dynasty.
It is very useful to use both the Beishi and its counterpart about the Southern Dynasties, the Nanshi, to gain a complete overview of the history of China during that age. Although Li's family came from the north many parts of the Beishi are not very detailed, so that the book is not often quoted in other books. Another shortcoming of the Beishi is that Li saw the Western Wei 西魏 (535-556) as the rightful successor of the Northern Wei, while the author of the Weishu maintained that the Eastern Wei 東魏 (534-550) was the lawful successor. This fact makes it all the more necessary for a historian to consult both sources.