I Transmigrated to Primordial Times and Became the Ancestor of Ghosts

A pure Primordial World story: no System, no harem, no heroine. The male lead is all about his career. The protagonist unexpectedly transmigrates back to the Primordial Era and becomes the progenitor of the Ghost Clan. He battles the Demon Emperor, establishes the Underworld... And crushes the Sages of the Primordial Era. So what if they're Sages? They'll still have to bow and pay their respects before me.