Complex sentence: During the Song Dynasty, narrative element in dance, for example the Sword Dance may include the story of the Hongmen Feast, led to the development of techniques in performances in Chinese opera.
Split into simpler sentences: During the Song Dynasty, a narritive element was added to the dance, for example, the Sword Dance included the story of the Hongmen Feast. This narrative element eventually led to the development of techniques in performances in Chinese opera.