You should be talking about Bai Juyi's Song of Eternal Sorrow.
Song of Eternal Sorrow is a long narrative poem by Bai Juyi, a poet in the Tang Dynasty. The whole poem vividly describes the love tragedy between Xuanzong of Tang Dynasty and Yang Guifei. With the help of historical figures and legends, poets have created touching stories and reproduced the truth of real life through their own artistic images, which have infected readers for thousands of years. The theme of this poem is "Song of Eternal Sorrow". This poem has had a far-reaching influence on many literary works in later generations.
The poem harmoniously combines narrative, scenery description and lyricism, forming the lyrical characteristics of the poem. Love is lingering, and books hate endlessly. The words are sad and touching, and the tone is melodious and often new. The stories and characters in poetry are artistic, and they are complex and true representations of people in reality.
In this narrative poem, the author describes the love tragedy of Xuanzong and Yang Guifei in the Anshi Rebellion with refined language, beautiful images, narrative and lyricism: their love was destroyed by their own rebellion, and they were endlessly eating the bitter fruit of this spirit. 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.