In the era of the prosperity of the human race, the strength and foundation of the demons were not weak. Relying on their special cultivation system and harsh environment, they could resist the extreme suppression of the human race. Even if many Immortal Dao experts attacked, they could not really eliminate the invasion and infiltration of the demons. After the appearance of the Myriad Spirit Ranking, as the human race gradually weakened and the demons lost the restraint of suppression, the range of infiltration of the various worlds became larger and larger.