Also known as "alliance" and "loyalty". Commonly known as "become sworn brothers". The communication folk custom of ancient Han nationality. Popular all over the country. That is, close friends become brothers with different surnames. It originated very early and is a small group of people with the same interests. Usually a few people, more than a dozen people. Vow forms mostly take the form of drinking blood against wine, kowtowing to relieve guard, swearing to heaven, etc. , so as to restrain and maintain the pledge relationship. After the Ming and Qing Dynasties, influenced by the stories of Liu Bei, Guan Yu and Zhang Fei in the Romance of the Three Kingdoms, * * * founded the country, and it became a common practice to become sworn friends. From ordinary people to literati, it was called "Jin Lan with meaning". Its meaning comes from the Book of Changes: "If two people get together, their interests will increase gradually;" Words of one heart stink like moss. "The exchanged post is called" Spectrum "or" Lan Spectrum ",which says that XXX, a sworn friend, and others voluntarily become half-brothers (or sisters) because of their deep friendship, indicating their names, native place, age, eight characters, names, origins and official duties of three generations. On the year, month and day of the oath, the sworn friend shall sign and seal or press the handprint. After offering sacrifices to their ancestors, they exchanged positions with each other and then became brothers. The two not only associate as brothers, but also their families associate as relatives, calling each other "godmothers". This custom mainly reflects the needs of unity and mutual assistance of small and medium-sized producers in feudal society. Bandits and bandits in Jianghu often use it to connect ministries. Its special emphasis is "sharing weal and woe, sharing weal and woe". The relationship between them is "brothers and sisters" or "brothers and sisters", commonly known as "brothers who exchange positions" and "brothers who become sworn brothers". This custom is disappearing today. " "Taiping Yu Lan" Volume 407 quotes: "Zhang Cai is around Wei, worshiping the corps commander and hiring Shu, and has a good relationship with Zhuge Liang. Tang Feng Zhi Yun Xian Miscellaneous Notes: "Dai Mei has a close friend, and he writes a book with thin bamboo slips, burning incense to tell his ancestors, with the number as. "A Dream of Red Mansions, Chapter 66:" I didn't want my second brother Liu to come from there, so I drove the thieves away, regained the goods and saved my life. I thanked him and didn't accept it, so we became sworn brothers. "