Since they both used wind attributes, and given that Youshen was once Qian Renxue's teacher, Youshen and Qingluan Douluo were not entirely strangers in the past.
Or rather, among the Seven Elders, Qingluan Douluo had the closest relationship with Youshen.
Although Youshen had previously exposed his Martial Soul, he had strictly used only wind-attribute powers.
Chapter 121