I am looking for a book with a female protagonist that has red hair.
Her family and culture are seafaring, I feel like they are similar to Vikings. They are merchants, and she (I can’t recall if she stows away on the ship or is allowed to come with because she is finally of age) travels with her father to another continent. The culture there doesn't allow their women to be seen in public, and they must be covered head to foot at all times. One woman in particular was engaged to be married to some lord’s son, a particularly vile boy, who beats and sexually assaults his servants.
Protagonist arrives at this market, and climbs their giant sacred rock (she has some connection to stone, rock magic, something). A bunch of old dudes from this patriarchal culture see her standing majestically on the rock, red hair streaming, where no woman is supposed to ever go. In order to protect her, the father cuts off her hair, maybe dyes it black to make it seem like she’s a boy.
After that, it gets real fuzzy. Civil unrest is sparked, some tents burn... the young lady that has to be covered all the time runs away?
The end is a war scene, the Viking-esque society is attacked and a town destroyed...
The cover is light blue, and I think features the protagonist sitting on a big ass rock.