To fake their identities as exchange disciples....
First, Ming Zixin and He Jingyi needed to kill the real disciples of Baiyun Sect who were coming to emerald jade mountain. Ming Zixin had heard some rumors as to how Jianyu Sect made exchange disciples from other sects overcome a challenge of ascending emerald jade mountain using thousands of mountain stairs.
So he had already expected that, even if Baiyun sect disciples used transportation talismans to come here, they would have to stop just at the base of the mountain.