During the reign of Emperor Wu of Han, after decades of recovery and development in the early Han period, society, economy, and culture had greatly advanced. To consolidate his rule, Emperor Wu adopted the Confucian scholar Dong Zhongshu's proposal to "dismiss the hundred schools, revere only Confucianism," decreeing that only those proficient in Confucian doctrine could be recommended for official positions.
Emperor Wu of Han elevated the five Confucian classics—the *Book of Songs*, *Book of Documents*, *Book of Rites*, *Book of Changes*, and *Spring and Autumn Annals*—to official status, naming them the Five Classics. He then established professors for these texts at the Imperial Academy, where they taught exclusively to students. Those who excelled in examinations could secure government posts, with top performers earning high-ranking positions. At its peak, the academy enrolled up to three thousand students.
By the time of Emperor Xuan of Han, Liu Xun, Confucian teachings had become even more dominant. Liu Xun himself was deeply influenced by Confucianism and summoned the renowned scholar Xiao Wangzhi to tutor the crown prince. However, since Confucian scholars offered various interpretations of the Five Classics, Emperor Xuan decided to hold a grand debate on the controversial portions of these texts.
In 51 BCE, Emperor Xuan of the Han Dynasty ordered his imperial tutor Xiao Wangzhi to host a grand debate at the Stone Canal Pavilion, the royal library and lecture hall. During the discussion, Confucian scholars banded together with those who shared their views, branding dissenters as "the other party," and united to attack them. The historian Fan Ye, author of the *Book of the Later Han*, later described this behavior as "siding with one's own faction and attacking all others."
Later, the idiom "side with one's own faction and attack dissenters" came to describe favoring one's allies while targeting outsiders.
Source: *Book of the Later Han*, "Preface to the Biographies of the Proscribed Partisans"
Meaning of the Idiom: Later, the Chinese idiom "党同伐异" came to describe favoring one's allies while targeting outsiders.