Four people in the early Tang Dynasty were called "Four Friends of Articles" by people at that time. They are Cui Rong, Li Qiao, Su Wei Dao and Du. Their works are similar in style, and the content is nothing more than praise and palace banquets. However, in some of their other works, sometimes the news of poetry reform is revealed, and some have made positive contributions to the construction of poetry system. Since the late Emperor Gaozong, they have been friends with poetry, hence the name "Four Friends of Articles". Among these four people, Du achieved the highest achievement.
The four major love dramas in the Yuan Dynasty were Guan Hanqing's Moon Pavilion, Wang Shifu's The West Chamber, Bai Pu's Immediately on the Wall and Zheng Guangzu's Ghost Story.
A dream of red mansions, that is, the study of a dream of red mansions, spans many disciplines such as literature, philosophy, history, economics, psychology and traditional Chinese medicine. Scholars in the Qing Dynasty used traditional methods to study A Dream of Red Mansions, such as chanting, commenting and exploring, which was called Old Dream of Red Mansions. Around the May 4th Movement, Wang Guowei, Hu Shi, Yu Pingbo and others introduced the modern western academic paradigm to study A Dream of Red Mansions. As a serious knowledge, Dream of Red Mansions entered the academic forest, and it was called the New Dream of Red Mansions, which was also called the three schools of thought in the 20th century with Oracle Bone Inscriptions and Dunhuang studies.