同舟共济
In ancient times, the people of the state of Wu and the people of the state of Yue had always been hostile to each other, which could be called feud（不和，争执）.
But if they were on the same boat and encounter a storm, they would help each other just like one's left hand coordinates with his right hand, and they didn't seem hostile to each other at all.
古时候生活在南方的吴国人和越国人素来相互敌视，可以说是世仇。
但假如他们同乘坐一条船渡河，遇到风暴的话，他们也会互相帮助，就像一个人的左右手互相配合那样，一点也不会像是仇人。