I don't know any documentaries off the top of my head (most of the documentaries on Chinese history that I know are either too focused or overly romanticize China, like reffering to Qin Shihuangdi as "The First and Most Glorious Emperor of the August Qin State"), but might I recommend "China: A History" by Harold Tanner? It's under 200 pages long, yet gives an incredibly accurate and concise review of China's history from the neolithic era to 1799. There is a followup book, covering China from 1799 to the modern era.

I know that this wasn't the answer you were looking for, but hopefully it may be a springboard that can lead you to some wonderful and more narrowly focused documentaries.