Is there a single period in known Chinese history that wasn't one or more of the following: What do you mean by period ??? - is 200 years of peace & properity a 'period' in your definition. Is multiple 100 year periods good enough ???
I had a list of criteria (one of which was lasting 150 years). You can't name a period in known Chinese history that doesn't have at least one of the criteria. Well, the Han dynasty was relatively peaceful, but was falling into corruption at the end and still was about total control (and the inability to keep it due to rebellion).
Fractured into multiple opposing regimes ??? When ???
403-221 BC, 220-589 AD, 618-907 AD, 1644-1949 AD.
Controlled by a brutal dictator or emperor ??? Brutal, in what context ??? (all rulers in almost all civilizations between 1000bc to 1700ad 'controlled' their subjects. This statement really means nothing).
I don't submit to the idea that something is ok, just because it's the fad at the time. People have consciences, and a brutal execution now or 1500 years ago is still a bad thing for the one being executed.
Controlled by a brutal totalitarian concept (Do you mean Mao ???, if not then which ruler ??? and brutality in what context ???)
Communism (as practiced by China) has been pretty good at being a brutal totalitarian way of life. In recent times they're getting a handle on it and gradually changing to a more representative form, but there a definitely some human right issues. Legalism was a parallel from a couple thousand years earlier; opposing views quickly quashed by destroying them in whatever form they came.
Majority of people living in poverty Sorry but this is pure crap unless you mean 19th century China as it was transitioning from feudal, to occupied to Communism). If so that is one tiny period in a great & illustrious history spanning 2 millenia !!!
There isn't much written about China outside of the elite class. Granted, everyone else survived, but it wasn't until the twelfth century AD that the population's food problems were met as a whole. Even then, you had rice and you had mud. Enjoy. The state of the majority of the population did not change from then until recently.
Just a few notes on the rest of your comments:
You underplay brutality and dictator control as the very beginning, by saying it was the way it worked then. Doesn't change what it was, and all the periods mentioned contained some aspect of that style of government.
Tang: Exemplified by one of the cruelest systems in known history. Look up Empress Wu. (Wu Tang...ring any bells ;-) )
The rest of the progress and achievements you mention were restricted to the few privileged (like many other governments in other regions). Most people ate their rice, sold the rest to pay taxes, sat in the dirt, and died when it was convenient.
This is not to underplay the rich documented culture and history of the Chinese elite. I merely pose that they don't have that much more to brag about than the rest of us. Each succesive regime change did manage to capture all of China rather than parts of it, but I'm not sure that qualifies them to claim expertise in proper governmental policy.