The Sweeping Monk of the Forbidden City

I spent fifty years restoring cultural relics at the Palace Museum. After dying peacefully of old age, I was reborn as a menial servant in a fantasy world, where sword immortals roam and demons lurk everywhere. They mocked me as an ordinary mortal, fit only to sweep the floor. Then one day, the demonic clans breached the sect's protective grand formation, and an utter calamity descended. I silently picked up my broom and drew a line before the skies full of demonic clouds. From this line onward, humans may pass. Demons and monsters are forbidden.