Before the T'ang period, the composition of official history had been the concern of two separate groups of officials: the court diarists, responsible for keeping the day-by-day record of the activities of the emperor and the court, and the Office of Literary Composition, responsible for the actual writing of the national record. This division of functions continued under the T'ang but became far more complex

The court diarists

The existence of court diarists can be traced back to the dawn of Chinese recorded history. The diarists of T'ang times saw themselves as the successors to the various recorders mentioned in the Chou li and to the recorders of the left and of the right (Tso-shih, Yu-shih) mentioned in the Li chi and in the Tso chuan. According to a tradition generally believed in T'ang times, the functions of these officials had been strictly distinguished, the recorder of the left having been responsible for noting down the emperor's actions, the recorder of the right for taking down his words. T'ang scholars believed that these two officials had produced distinct types of records from which had originated two separate genres of ancient historical writing.