It is simple. Yan people treated them like animals, so, to the eyes of the Great Steppe, how could the people of Yan get their loyalty?
The lord of the Steppe that knows to treat the warriors and the people of the Steppe, the people of the forest, the people of the river and mountain, the people who Yan called "barbarian" with sincerity could win their hearts, so they would repaid it with their life.
People everywhere is the same.
There is some differences here and there, but most people share the same desires, likes and hates.
Everyone would be sincere to people that are sincere to them and everyone would be insincere to people who are not sincere to them
The most sure-fire way of winning people hearts is being sincere to them. Poor people, rich people, even powerful people could be moved by sincerity
If even powerful people are moved by sincerity, it would work even more potent for poor people.
