Looking back at the smile, Bai Juyi's Song of Everlasting Regret came from the Tang Dynasty. This poem described the tragic love between Emperor Xuanzong of the Tang Dynasty and Yang Yuhuan, and the poem "Looking back and smiling, a hundred beauties grow" was one of the poems that described Emperor Xuanzong of the Tang Dynasty being moved by Yang Yuhuan's smile. There was a similar poem in Du Fu's "Beauty's Journey" of the Tang Dynasty: "The snow falls on the willow flowers and covers the white apple. The blue bird flies to the red scarf. You're hot and powerful. Don't come near the Prime Minister and get angry!"