The Snares of Ibex (Diadem Novels, Book 8)

From the back cover: Aleytys had searched for her mother across the worlds of the inhabited galaxy. Her mother was of a super-race; her homeworld's location a secret. But Aleytys had become an expert star hunter, alert to clues and wary of danger -- and she knew that on Ibex her ancestral trail must reach its end. But Ibex was an unmapped world banned to outsiders -- save for one encircled city. To venture beyond that enclave meant death, for the many alien native tribes were united only in their lust to slay all other-worlders. All the Snares of Ibex awaited Aleytys beyond the wall -- but dare she must if her life was to have any future meaning.