Complex sentence: In some sources she was said to be the sister rather than the daughter of the king who was actually incarcerated by her brother and to escape from the ignominy of incarceration she jumped to death from the top of the tower.
Split into simpler sentences: In some sources she is said to be the sister, rather than the daughter, of the king who came to be incarcerated by her brother. To escape from the ignominy of incarceration, she jumped to her death from the top of the tower.