It serves the interests of a political elite to promulgate a feeling of great utility to them that “we’ve always been here, we are ever-present now, and there is no reason to suspect we will always exist into the future”. It serves to bolster legitimacy assertions upon geographic locales, based upon “ancient claims” or at least “claims older than yours”. This continuous-unbroken-culture-thousands-of-years-old notion I find peculiarly culturally specific. It is an amalgamation made up of Confucian respect-to-elders and venerate-the-dead I don’t agree with when the venerate-the-dead aspect comes at the expense of those living in the geographic locale, and those at the top peculiarly benefit in their pocketbooks to enforce this “ancient tradition”.
The US and indeed most major nation states also use this kind of myth making as well, this kind of behavior isn’t specific to China. It’s just not taught in schools.