Chen Mobai honestly didn't know this.
"The Cinnabarite Institute's 'The Union of Differences' and 'Pure Yang Scroll' were passed down by Yun Ya, one of the five founders of the immortal sects," Qing Nu began.
"As the story goes, Yun Ya was actually a Supreme Elder of the Dan Ding Sect, one of the original patriarchs, before coming to Earth. These two cultivation techniques were fundamental to his sect, and he practiced 'The Union of Differences' himself and used it to ascend to become Immortal," she continued.
"The 'Pure Yang Scroll,' due to the difficulty of finding those with the Pure Yang body required for its inheritance, was kept with him for a long time. It wasn't until thousands of years after he started to cultivate at the Immortal Gate that Yuan Yang was able to successfully practice it," she finished.
Qing Nu recounted these facts as if listing cherished family heirlooms, causing Chen Mobai to nod along in continued agreement.