The traditional account of ancient China, represented by the "Records of the Grand Historian" written by Sima Qian in the Han dynasty, begins with the Three Sovereigns and Five Emperors, leading through a sequence of dynasties, the Xia, Shang and Zhou. Sima Qian felt able to give a year-by-year chronology back to the start of the Gonghe Regency in 841 BC, early in the Zhou dynasty. For the period before that date, his sources (now mostly lost) were unreliable and inconsistent, and he gave only lists of kings and accounts of isolated events. Later scholars were unable to push a precise chronology back past Sima Qian's date of 841 BC.