Hmmm. I think we can add the opposite quality from the Wind- their words are marked in stone.
Ghost stories are popular because
Honesty and the way the sacre promises, make them very trust worthy, which is actually good for buisness.
The Wind people view them as foolish, and they view the wind people as corrupted bastards.
Also, many times mountain civilizations are herders and/or hunters.
I can also imagine them more connected to the nature, and maybe have tradional speciality around this.
Also, I don't think they would have a very devolped nobility- usually nobility in the feuadlic sense based on farmers.
I think maybe they would be led by shamans and priests?
I imagine for them Aibu astetic-

(It's a mountain tribes from Japan... more ancient then the japanese.)
Anime examples

You know, they were driven off, by the japanese. Maybe, they actually remains from an ancient people, and have actually a good historical reason to mistrust forigeners.

Also maybe they are allied with the
Fairy-ish like people.

I mean.. many times in media, it shown like.
"Oh, those goofy people cling to silly customs. How barbaric'

But, usually there are benefits from such view. And I think we can give them druidic/shamanic edge, and so give them their own spin.

Just an idea.