The best overall source for the period of Yü Hsin's life is the Tzu-chih t'ungchien, by Ssu-ma Kuang (1018–86) et al. The work has the advantage of drawing on a number of sources now lost and provides, in convenient chronological arrangement, a good deal of information not to be found in the official histories (for example, the date of Yü Hsin's mission to the Western Wei). Even Ssu-ma Kuang could not make bricks without straw. Many of the earliest sources had disappeared long before him, and also, especially for the Northern Chou (557–81), the records were apparently never very complete. The Tzu-chih t'ung-chien has the additional advantage of an excellent commentary by Hu San-hsing (1230–1302).

Yü Hsin's life is divided into two periods: that under the Liang, down to 554; and that under the Western Wei/Northern Chou. For each period there are two complementary works among the official histories. The earlier period is the better documented, with the Liang shu, compiled by Yao Ssu-lien (d. 637), and the Nan shih, by Li Yen-shou (fl. 629). The Liang had been the subject of a number of contemporary or near-contemporary histories, some of which are discussed in Erh-shih-wu shih pu-pien, pp. 5252a–53a, 5265c–67c. Most of these survived long enough to be used by the ‘T'ang historians. It is, of course, difficult to judge now exactly what use they made of them, but, probably as a result of this rich documentation, the Liang shu is much the best of the four official histories that concern us here.