After the " fall " of the true dragon Lord, the slough that was separated out was obtained by doldie. His initial research direction was to " slice " the slough into thousands of pieces and resolve the spiritual will contained in the slough in this way.
But he failed.
Slicing couldn't dissolve spiritual will. It was still left in the body. Moreover, the split bodies could sense each other and automatically gather together.
It was not until more than a hundred years ago, when duo Erdi was studying the array of the unparalleled war spirit, that he finally made a breakthrough and split the slough into two.
The main shed always carried it with him. He had sealed the small piece of the shed in a well with a formation.
Many years later, when he returned from a certain trip, duo Erjie found that the small piece of shed skin had grown wildly and turned into a small black Dragon. However, due to its incomplete spiritual will, the Black Dragon's intelligence wasn't high.