桃园三结义/ 桃園三結義 táoyuánsānjiéyì Oath of the Peach Garden
The famous oath sworn by 刘备 liúbèi, 关羽 guānyǔ, and 张飞 zhāngfēi in a peach garden at the beginning of the classic novel 三国演义 sānguóyǎnyì; it describes people who are not blood relatives becoming sworn brothers