Prehistoric Tales of the Star-Tang United Empire

On the great journey of intelligent civilizations toward the infinite stars, they must face one Great Filter after another. Crossing the threshold into industrial civilization already means passing one Great Filter. Developing technologies such as controlled nuclear fusion and crossing the threshold to a Type I civilization means facing another. Mastering the power of atomic energy while also preventing civilization from collapsing under its own internal strife while still on its homeworld: that is yet another Great Filter! During the unification of the homeworld, having no equal enemy is no longer the point. Avoiding an Easter Island-style dead end during the homeworld civilization stage and breaking through one Great Filter after another: that was the epic tale of the past! This is that distant, long-buried history, the story of what happened before the birth of the artificial intelligent beings known as the "Star Tang Walkers"! The two protagonists are reincarnated on Earth in another parallel universe. As it happens, it is the Tang dynasty in the mid-seventh century. In time, they will be hailed as the mother and father of the Star Tang Walkers.

PS: This work could also be titled "After Two Humanoid Super Beings Unify Earth, They Become National Idols While Preparing to Reach for the Stars"