Tian Xia has been in existence as a continuous entity for approximately the last 1000 years. It’s gone through 7 dynasties, with the usual route of change being a noble revolting against the current emperor (Huang Di), and succeeding, demonstrating that the previous dynasty had lost the “Mandate of Heaven”. One of the dynasties was a short lived one that resulted from a successful invasion by a barbarian tribe. Another was a result of usurpation by the Grand Vizier. This was the rise of the citizen class, which would eventually end up receiving its own house in the legislature.