Complex sentence: She was the illegitimate daughter of King Edgar the Peaceful, by Wilfrida, or Wulfthryth, a woman of noble birth whom Edgar carried off forcibly from the nunnery at Wilton Abbey.
Split into simpler sentences: She was the illegitimate daughter of King Edgar the Peaceful. Her mother was Wilfrida, or Wulfthryth, a woman of noble birth, whom Edgar carried off forcibly from the nunnery at Wilton Abbey.