The Ulan Star is a Star located in the Edge of the Great Southern Heavenly Realm and a Star that is ruled in the domain of the Yun Lan Holy Land. It's grand opportunity would be it's Spirit Core, which can generate the unique Spirit Stones of Ulan Star.
It's main forces is the Four Families, who would wait for the Spiritual Fog of the Spirit Pit to open, so that they can mine it for the Holy Land, making them capable of having some of their members entering the Holy Land and the Families would be given Immortal Fruits.
In Chen Fan's Previous Life after he became a Void Returning Cultivator, his Divine Sense exploded and discovered the existence of the star and took it's Spirit Core, which makes the Yun Lan Holy Land bore a grudge against him. Chen Fan also stole it in his Current Life in a much, much earlier time than his previous life.[1]