Tianyu, where Xu Ping'an resided, was indeed one of the six counties of the Great Qin Immortal Dynasty.
In the Mortal Realm, there are four great Immortal Dynasties in total, namely: the Great Flame Immortal Dynasty, the Earth Spirit Immortal Dynasty, the North Chill Immortal Dynasty, and the Great Qin Immortal Dynasty.
For the people of the Mortal Realm, entering the Spirit Realm is extremely difficult.
One must have an invitation from the Spirit Realm to pass!
Therefore, each of the four great Immortal Dynasties is supported by a corresponding Spirit Realm.
The spiritual energy in the Mortal Realm is extremely sparse, while the Spirit Realm's spiritual energy is a hundred to a thousand times denser than that of the Mortal Realm.
For this reason, strong individuals in the Mortal Realm all wish to cultivate in the Spirit Realm.
The four great Immortal Dynasties would also send some talented individuals to the Spirit Realm for cultivation to strengthen their own powers.