Ronia the Robbers Daughter by Astrid Lindgren

Plot

Ronia grows up as a half wild child and knows her woods like the back of her hand. But when the Borka robbers (the mortal enemies of her father, Matt) move into the other side Matts castle Ronia meets Birk (the son of the Borka chief) her life changes forever.

Best bit

When they tame wild horses

Pages until you are hooked

It took me a chapter to really get into this story but do keep reading!