Complex sentence: For a while, Morgase was a prisoner of the Children of the Light, and during this time she signed a treaty allowing the Children of the Light entry into Andor as a power governed independently from the throne.
Split into simpler sentences: For a while, Morgase was a prisoner of the Children of the Light. During this time, she signed a treaty allowing the Children of the Light entry into Andor as a power governed independently from the throne.