Earth is the third planet from the Sun and the serve as the stage for majority of the events in the novel.
There are space channels (空间通道; kōngjiān tōngdào) that connecting Earth with various realms.
There are seven space channels connecting Earth and the Nine Serenities. These space channels are protected by an organisation called as the Channel Protectors, supported by various schools and sect from the Cultivator’s Alliance.
The space channels were protected by Earth’s Tribulation Immortals. Due to Changing Heaven, the Tribulation Immortals started to shun the world. They will only take action if the Nine Serenities Tribulation Immortals coming.
After the Collapse of the Heavenly Way, and the subsequent demise of the Eighth Nine Serenities Ruler, the Demons of the Nine Serenities swarmed the seven channels, hard pressing the Channel Protectors. Wang Lin, one of the protectors, requested help from Saint Monarch Tyrant Song at the urging of his fellow protectors.