5000 years for me. That's official!

But this seems to ignore the Yang-shao in Chung Yuan, which has the fundamental elements of the Hsia, Shang and Zhou. The Yang -shao possess considerable time depth back to six thousand bc.
"If we understand Chinese civilization to be the civilization that was first consolidated during the Ch'in and Han, Chung Yuan was but one of several major contributors, rather than its only ancestor. But there is little question that Yan-shao culture was in the direct ancestral ine that eventually developed toward the Hsia, Shang and Zhou civilizations of North China. These early historical civilizations were without question the most important contributors to the Chinese civilization. In this light, Yang-shao culture was in every sense an early "Chinese" culture."
KC Chang "Archaeology of Ancient China"
Here Chang uses the terms 'culture' and 'civilization' interchangeably, and indeed the elements that define the later dynasties are present in the Yang-shao. Ancestor worship, large-scale slash and burn agriculture, ritual pottery sets, stratified society with craft specializations; all evident in 6000bc. To differentiate the Yang-shao from the later political divisions (Hsia, Shang and Zhou), then one must ignore the cultural continuity of the three dynasties, which is untenable. So seven or eight thousand years is not unreasonable.