The Blue Sword
Harry Crewe is an orphaned girl who comes to live in the desert of Damar, seen as an outlander by both of the countries opposing factions, the Homelanders and the magical Free Hillfolk. When she meets the golden-eyed king of the Free Hillfolk, Corlander, it soon becomes clear that Harry is more powerful and important than she or anyone else would have guessed.
This teen fantasy, originally published in 1982, is a rip-roaring ride filled with fantasy, girl-power, romance and danger. McKinley creates a fully realised mythical land and throws in a modern-day heroine for good measure, resulting in quite the adventure.