Xian Jian Qi Xia Zhuan 4

For the sake of their cultivation endeavors, the Qionghua Sect sent its elders to forge two swords, Wangshu and Xihe, and sought two disciples to wield them in dual cultivation, attempting to bind the demon realm and seize its immense spiritual power. This ultimately triggered a great war between humans and demons, resulting in heavy casualties on both sides. During this time, Su Yu, the host of Wangshu, disagreed with the Qionghua Sect's cultivation philosophy and left the sect with Yun Tianqing. The demon realm seized the opportunity to escape, and the Qionghua Sect's leader perished in the war.

The two married on Qingluan Peak and had a son, Yun Tianhe. They both died young due to the icy cold that invaded their bodies. Young Yun Tianhe grew up alone on Qingluan Mountain. He was unaware of his parents' past, and the unexpected arrival of Han Lingsha set the wheels of fate turning once more.

(Source: Bilibili, translated)