In ancient times, the four brothers were arranged from eldest to youngest: Bo, Zhong, Shu, and Ji. Bo was the eldest, Zhong was the second, Uncle was the third, and Ji was the youngest. It comes from "Zuo Zhuan·The 26th Year of Zhaogong" written by Zuo Qiuming in the pre-Qin period: "Only Bo Zhong and Shu Ji draw it." This means that the order of elder and younger is divided in this way.
Bo, Zhong, Shu and Ji were often used in ancient times to express names or honorifics for people. Sun Jian had four sons, the eldest son Sun Ce was named Bofu, the second son Sun Quan was named Zhongmou, the third son Sun Yi was named Shubi, and the fourth son Sun Kuang was named Jizuo. This is quite representative among the characters chosen according to Bo Zhong and Shu Ji. The ranking of "Boss, Zhongshu, Ji" is suitable for families with four brothers or less. However, in ancient times, there were also many families with more than four brothers. After the "fourth brother", they were all called "Uncle" or "Uncle". certain".
In ancient my country, the ritual and music system was relatively strict, with strict requirements for patriarchal etiquette and respect for elders and younger ones. Titles can reflect rank, status, reputation, etc.
China has been a land of etiquette since ancient times. In its long history, it has formed a relatively special system of titles of its own.