The hidden world was an environment filled with ancient species and forgotten creatures, but it wasn't useful as a territory. Nothing could beat the piece of Immortal Lands in terms of resources and density of "Breath".
Noah had been ready to leave that place as soon as he restored the powerhouse's body. Still, the rebels had no intention to leave before saving as many tribes as they could.
Since Noah wasn't willing to leave without the Seventh Kesier rune and those heroic assets, he decided that it was time for him to help them properly.
That wasn't his first rebellion, and he had become used to wars throughout his life. His experience in battles of that kind and his prowess could help the rebels end that matter faster.
Noah went on a solitary exploration once his dantian reached the solid stage. He had yet to adapt his techniques to his new power, but the process would be faster if he had opponents that could endure his blows.
