Yindu and Yan and the Great Steppe

The reason why the people of the Steppe teaches Xiahou Cao all kinds of tactics and even fought in his army, is because they believe in the sanctity of a promise, of an oath

The tribes of the Great Steppe hold their principles and values in high esteem, especially when it comes to promises and oaths.

  For them, a promise is not a trivial matter; it is a solemn vow that carries the weight of honour and integrity. 

When they make a commitment or pledge, they do so with the utmost sincerity, and they expect others to uphold their promises in the same manner.

This strong belief in the sanctity of oaths has led the Steppe people to share their knowledge of tactics and even fight alongside Xiahou Cao army. 

They extend their trust, believing that he will honour his word and treat them with fairness and respect. 

They see this cooperation as a gesture of goodwill and hope for a future of mutual understanding and cooperation.