White Dragon Sovereign was originally from a Lower Plane, but was forced to escape to the Great Thousand World when the plane was invaded by forces of Blood Demon Clan. [1]
He was once a powerful Sovereign expert of the Demonic Dragon Palace. But, because he was in disagreement with the direction of the Palace, especially the war, he chose to betray the Palace, steal the Great Meru Demonic Pillar and run away with it. He was met with great resistance from the other Palace's Sovereigns, but managed to escape using his Dragon Soaring Art. He later died in the White Dragon Hillock.
When his Spirit Treasury appeared in the White Dragon Hillock, Mu Chen managed to acquire the Great Meru Demonic Pillar and White Dragon Spiritual Pearl, while Black Dragon Sovereign's Clone was fighting against the remnant spirit of the White Dragon Sovereign. [2]
Mu Chen later broke the seal of the White Dragon Spiritual Pearl and encountered the White Dragon Sovereign's Will within the Pearl. The latter then told the former to absorb as much of the Spiritual Energy in the Pearl as he wanted, after that was done he gifted Mu Chen the Dragon Soaring Art, and told him about his past in the lower plane. He also promised Mu Chen, that if he managed to exterminate the Blood Demon Clan in his home plane, he'd gift him an opportunity that would let him become a true supreme expert. [3]