So, I have an empire, many political notes about which can be found here, although I will put more relevant notes here as well.
There are many fantasy races, all of them some form of animal person, they are of varying size and capabilities. Notably, within this setting, humans are actually regarded by themselves and the other races to be human person. They have a pantheon of common divine creators, as noted here.
Due to the circumstances of their creation, they are actually the same species, so they can and do quite often marry between races. For genetic inheritance, gender-based races are a thing, so the male children are the same race as the father while the female children are the same race as the mother. The children are no worse than any actual "pure-breeds".
So, how do I allow these people to not fall into all-out racial based wars of the 10th century world?
Do note that minor racism would be allowed, like some races thinking other races are not as clean as them, I just want to make sure that these races can be quite different, and would rather work together within their nation rather than their race.
To clarify, how to make promote nationalism amongst these different races so that they would work together to be able to beat other nations/kingdoms, both in a military and a economic standpoint, to make the bonds of nationalism stronger than racism
For example, kingdom A has a notable dog people, human, and cat people population; kingdom B has a notable dog people, cow people and horse people population. Even if the dog people of kingdom A do not quite like the cat people of kingdom A, they will work for kingdom A, against kingdom B, against their own race.