When Di Jiu had still been in the Qi Refinement Realm, he had used the Ninth Dao Law to help open up Geng Ji's galaxy meridian. Now that he had established his cultivation technique, he formed the Ninth World with the Ninth Dao Law and the Sacred Yin Pearl along with his Spiritual Sea that had transcended nirvana. He wanted to open up the Starry Sky meridian for Ah Xi, Yan Yumo, and Xiangnu, which seemed effortless.
After opening up their Starry Sky meridian, the three of them cultivated under the Spirit-Gathering Array Di Jiu set up using supreme-grade spirit meridians and seemed to make rapid progress.
The three of them survived battles all year round. Di Jiu was not worried about their future survival. Plus, they were not considered young anymore, so he had to let them increase their cultivation level frantically.
In just a few months, the three of them broke through to the mid-stage Qi Refinement Realm and kept steadily improving.