Complex sentence: Her paternal grandparents were Robert II of Artois and Amicie de Courtenay, and her maternal grandparents were John II, Duke of Brittany and Beatrice of England, the daughter of King Henry III of England and Eleanor of Provence.
Split into simpler sentences: Her paternal grandparents were Robert II of Artois and Amicie de Courtenay. Her maternal grandparents were John II, Duke of Brittany and Beatrice of England, the daughter of King Henry III of England and Eleanor of Provence.