Dave Schuler has a good little post which points out that there’s a big difference between ancient history as it happened and ancient history as we know it.
According to the Official Chinese History, the Han Chinese have lived within roughly the modern Chinese borders for more than two thousand years, Chinese culture is five thousand years old, the Chinese invented practically everything before anybody else, and Chinese culture sprung up completely independently, uncorrupted by outside influences. Unfortunately for the Official History the evidence for all of these things is passing small and coming under strain as we uncover more and more about the past and what happened in really truly history.Chinese scholars knowingly invented much of this Official History during the same period that in Europe we call the Middle Ages. The really truly history is a lot more complicated. than the Official History would have it.
There have been other non-Han Chinese people living within what is now China from time immemorial. Some have been non-Han Chinese East Asian peoples. Some have been Central Asian peoples. Some have even been people of European type. China has been influenced by all of these people. Its culture did not develop in isolation and in many ways in antiquity China was a technological backwater.
Read the whole thing. This is always worth keeping in mind when you’re reading about history. Don’t just look at accounts–look at evidence.

My impression is that most people don’t understand the difference between primary and secondary sources. This is a big factor in dealing with ancient history when much of what is “known” comes from ancient secondary sources who are being treated as though they were primary sources. What passes for confirmation is a actually multiple secondary sources all of which are quoting the same singular, uncorroborated primary source.
That’s a factor in recent events, too. A great example of this is the removal of Mossadegh. There’s a prevailing narrative, derived as best as I can tell entirely from secondary sources. The primary sources don’t agree on the subject.