During the fall of the Qin Dynasty, Xiao He followed Liu Bang through countless battles. When Liu Bang's forces captured the Qin capital Xianyang, while other officers scrambled for gold and treasures, Xiao He rushed to secure the imperial archives—laws, maps, and census records. He understood that knowing the nation's strategic passes, county populations, and social conditions was far more valuable than any loot. This foresight later proved crucial in governing the empire.
After the Han Dynasty was established, Emperor Gaozu Liu Bang appointed Xiao He as his prime minister. Having mastered the vast archives of the Qin Dynasty, Xiao He was intimately familiar with the entire realm, and thus crafted a comprehensive set of excellent laws, codes, and institutions for the Han court.
When Xiao He was gravely ill, Emperor Hui of Han visited him and asked, "Chancellor, who can take your place?" Xiao He was too weak to speak. Only when the emperor mentioned Cao Can did Xiao He nod.
Cao Can, a general who fought alongside Liu Bang in the uprising that founded the Han Dynasty, earned great military merits and was enfeoffed as the Marquis of Pingyang. For nine years, he served as the prime minister of the Qi region, where he governed using the principles of Huang-Lao philosophy, advocating for a policy of quiet non-interference—avoiding unnecessary disruptions and letting the people live in peace. His administration made Qi a model of good governance.
After Xiao He died of illness, Cao Can succeeded him as prime minister. Convinced that the entire system of policies, laws, and regulations Xiao He had established were practical and effective, Cao Can saw no need for change. He governed strictly by Xiao He's old rules, a steadfast approach that greatly helped stabilize the early Han dynasty.
Western Han writer Yang Xiong wrote in "Jie Chao": "Xiao He's laws and regulations were followed without change by Cao Can; Marquis Liu Zhang Liang devised strategies; Chen Ping launched six surprise attacks; their merits towered like Mount Tai, their fame resounded like an avalanche."
Later, the idiom "Xiao's Rules, Cao Follows" came to mean later generations following the precedents set by their predecessors.
Source: Yang Xiong (Han Dynasty), *Jie Chao*
Meaning of the Idiom: Later, the Chinese idiom "萧规曹随" came to describe later generations following the precedents set by their predecessors.