It is recorded in The Biography of Yang Taizhen that Li Longji, Emperor Taizong, once compared Haitang to Yang Guifei, indicating that there are many Haitang plants in the palace. The origin of the allusion of "Haitang Sleeping in Spring" is related to Tang Huang Ming and Yang Guifei.

Source: Tang Juyi's Song of Eternal Sorrow

Original text:

However, due to the gift of heaven and no concealment, it was finally elected royal one day.

If she just turned her head and smiled, there were a hundred spells, and the powder and paint of six palaces disappeared without a trace.

Translation:

The Yang family has a daughter who has just grown up and is kept in a boudoir. Outsiders don't know that she is absolutely beautiful.

Natural beauty made it difficult for her to be buried in the world, and soon she became a concubine around Tang.

Extended data:

Appreciation: Song of Eternal Sorrow is a famous masterpiece in Bai Juyi's poems. Written in the first year of Yuanhe (806), the poet served as county magistrate in yi county (now Zhouzhi, Shaanxi). He visited Xianyou Temple with his friends Chen Hong and Wang Zhifu, and wrote this poem because of the story of Emperor Xuanzong of the Tang Dynasty and Yang Guifei. In this narrative poem, the author tells the love tragedy between Xuanzong and Yang Guifei in the Anshi Rebellion with refined language, beautiful images, narrative and lyricism.

Their love was ruined by their own rebellion, and they were eating the bitter fruit of this spirit endlessly. Tang Xuanzong and Yang Guifei are both historical figures. Poets do not stick to history, but rely on a little shadow of history. According to the legend of the people at that time, the singing of the neighborhood has degenerated into a tortuous and touching story, which is described and sung in a reciprocating and touching art form. Because the stories and characters in the poem are artistic, and they are the complex and true reappearance of people in reality, they can ripple in the hearts of readers in past dynasties.