It means that an arrow pierced the sky and opened the river of time. The majestic melody can't hide the heroic spirit, the spectacular war horse gallops, the pike pierces the sky decisively, the yellow sand in Wan Li is rolling, and the smoke and dust are mixed with the blood of soldiers.

This sentence is the lyrics of the song "Treading the Mountains and Rivers". These two sentences are metaphors of beautiful things before this background, which are in sharp contrast with the stories that follow.