Guardian of the Book of Orain by Alison Hyland

All Jennyver wants to do is to stay in her little room in Dargonele Abbey, read her books, and bide her time until her father returns to take her away to their new home in the south of Scarlosia. She finds herself in a cold world where customs are rigid and complex, music is forbidden, marriages are arranged, and people covet a legendary sword. She learns to her horror that she is expected to take her grandmother’s place as Leader of the Seven Tribes and command a formidable army in order to protect a legendary book that has been a carefully guarded family secret for over one thousand generations.