The Heavenly Dao sends down rainwaters named Spiritual Fiend. Countless seeds absorb the nourishment, among which some grow the largest, overshadowing one area. Their roots expand, absorbing more rainwaters, making themselves increasingly enormous, storing the most nutrients, and causing their shadowed areas to no longer produce new trees.
The Heavenly Dao believes this is not good, so it sends the 'Seven Fiend Tribulation' to destroy these giant trees, reducing them to ashes and compost, once again nourishing the earth.
This is the truth behind the Seven Fiend Tribulation.
On the surface, it seems to be just that.
But being probably the only top-level Seven Fiend Tribulation with both parents living, An Jing holds a slightly different view.
