Who is the allusion about whom the poem Danfeng is written is as follows:
1. Han Cuiping? Xizong of Tang Dynasty (862-888), that is, Li Yan. Emperor of the Tang Dynasty, Yi Zongzi.
2. One evening during the reign of Emperor Xizong of Tang Dynasty, young Yu You was walking under the city wall. It was late autumn when "the west wind blew across the Wei River, and fallen leaves covered Chang'an". The ground was covered with withered fallen leaves, the wind howled away, and the thorns of the branches of the trees looked like cracks in the ice in the cold air. The sky was getting darker and darker, and he stood blankly for a moment, feeling inexplicably sad. He washed his hands in the running water of the ditch. The fallen leaves floating in the ditch slowly flowed out in the clear water. Suddenly, he found a larger red leaf with ink marks on it. He picked the leaf up from the water. What surprised him was a poem inscribed on the red leaves: "Why does the water flow so fast? The palace is full of leisure. I thank the red leaves diligently so that I can go to the world." The ink marks were not dry yet, and the handwriting was delicate and graceful.
Danfeng literally means blood-red maple leaves. It also means that the leaves of maple trees are stained red after frost.
It is said that the reason why the maple leaves turned red was because of Chi You's death. His blood penetrated the maple leaves and dyed them red, which is well known to future generations.
The more famous allusions include the "Poetry on Red Leaves" allusion from the Tang Dynasty.