China's history seems to remain very detailed throughout it's entire time, even in it's early days and it seems to be lacking any kind of "dark age" of information similar to European history. Why is this, how did China manage to hold onto so much information?
China had the tradition of having "court historians" or "chroniclers" whose job was to record events faithfully and comment on the merits and wrongdoings within the court. This tradition was said to came from as far as the Xia dynasty. Throughout Chinese history, one of the greatest drives for emperors to do good was to leave a legacy good enough so his name and deeds will be remembered fondly in history (名留青史). It wouldn't be possible if the historians could easily be bought or coerced.
Historians were highly revered in ancient China because it was their job to not only record history, but also "review" the tenure of a ruler. There are documented events dating back to the Warring States period of court historians being mass-executed for refusing to rewrite history in favour of the rulers, so in most cases, the use of force or bribery to cover up events had a very high chance of backfiring.
One of the most famous examples of a historian being punished for speaking out is Sima Qian, also known as the father of Chinese historiography for his authorship of the Records of the Grand Historian (史记) (94 BC). Sima Qian was thrown in jail and castrated mainly because Emperor Wu thought Sima slandered him in his yet incomplete Records. The historian continued and completed his authorship in jail. Sima subsequently hid the completed manuscript in the residence of his daughter to avoid destruction by Wu and his successor. The completed work was finally disseminated by Sima Qian's grandson twenty years later.