Martial Inheritance

A boy named Shi Shan and his little sister were offered as sacrifice to a demon that has been haunting their village. They were rescued by a martial artist who exorcised demons. He took the siblings in as his disciples and taught them the art of cultivation and about the demons that dwell in this world.

Translated raw sypnosis:

He said, "This world fundamentally should not have demons." And thus, all the lands became peaceful.