The disciples from other sects couldn't double their strength like that. So they struggled to cross into the third section.
More than half of the disciples of other sects had to stop in the second section. The rest of them stopped at the third section.
Only a few disciples from the other sects could make it to the fourth section; most of them were from the Black Bones sect. The people after them were the disciples of the Beast Training sect.
The disciples from the Black Bones sect had the help of their corpses. While these corpses couldn't double their strength, the corpses could carry them across the mountains.
The corpses didn't last long because of the heat. They couldn't use an energy shield, so they were quickly burned up. But before they turned into ashes, the corpses helped their masters to cover some distance.
