The term “sworn brother” originally referred to a non-homosexual relationship（dating back to the Three Kingdoms period and earlier）However, during the Ming Dynasty, in Guangdong and Fujian, it evolved into a relationship somewhat similar to modern male homosexuality due to population imbalances. In the book 《万历野获编》, it says, “闽中契弟”乃“习尚成俗.” The term somewhat looked the same as in the previous dynasty, but the meaning had changed.

For a quick explanation, you can search for “契兄弟” on Baidu But if you’re really interested, I suggest reading a book called 万历野获编. It was published in 1989. The book covers the history from the early Ming dynasty to the end of the Wanli period covering many aspects like government systems, key people and events, historical storiess, class struggles, ethnic relations, foreign affairs, landscapes, classical literature, craftsmanship, religion, and supernatural tales. It’s a valuable resource for studying Ming dynasty history. Unfortunately, there’s no English version available.

This post has been edited by agility: Oct 16 2024, 11:08 PM

https://baike.baidu.com/item/%E5%A5%91%E5%B...%80%9D%E3%80%82

根据许多史籍和笔记的描述，福建是明代男同性恋比较公开与普遍的地区。当时，福建海运很盛，去菲律宾、台湾、日本等地通商的很多，而航海的人都相信，船上不能有女人，否则船会出事，这样，长期在海上的人就以同性恋作为性发泄。明代沈德符的《敝帚斋余谈》云：
近乃有称契儿者，则壮夫好淫，辄以多金娶姿首韶秀者，与沟衾裯之好，以父自居，列诸少年于小舍，最为乱逆之尤。闻其事肇于海寇云，大海禁妇人在师中，有之辄遭覆溺，故以男宠代之，而尊豪刚遂称“契父”。
“契”这个字，在福建就是指男性间的性关系。中国传统的同性恋的关系，当要受社会承认时，就要举行一种“契”的仪式，建立“契父”和“契儿”、“契兄” 和“契弟”等关系，在福建地区，这类关系很多，它和广东孤婆庄的妈祖阶层，都是中国传统的同性恋关系的表现。中国人受儒家思想影响很深，十分重视家庭关系和家庭形式，所以同性恋关系也要以父子、兄弟、姊妹相称。《敝帚斋余谈》中进一步提到这个问题说：
福建人酷重男色，无论贵贱，各以其类相结，长者为“契兄”，少者为“契弟”。其兄入弟家，弟之父母抚爱如婿，弟日后生计及娶妻诸费，俱取办于“契兄”，其相爱者，年过而立者，尚寝处如伉俪。
这种“契兄”、“契弟”的关系，不但为当时当地的道德、法律、风俗、习惯所认可，而且权利、义务关系也很明确，这就是“契兄”受到“契弟”父母的爱护和尊敬，像他们的女婿一样，而当“契弟”到了一定年龄要与女子结婚时，“契兄” 就要在财力上予以支持。