Blades from the Willows: A Chinese Novel of Fantasy and Martial Adventure

Published in 1946 (translated in 1991)! The story's writing style doesn't quite stand the test of time as it's practically all narrative summary, but it has a touching unrequited-love subarc--and if you want to know what xianxia was originally all about, you won't be disappointed. There are good Daoists (cultivators) and evil Daoists as well as evil Buddhist monks. There are the Miao who are stereotyped as primitive but have strong magic--still, one heroine is Miao. I've attached some text where they talk about sects and schools.