I sense a pretty weird dynamics between these two countries.
There is this one country that invades the neighboring country to seize their lands to secure food supply. Hardly justifiable, but understandable.
And then, there is this neighboring country, or rather, tribe, that has this weird tradition of marrying its chiefs to female warriors from previously mention nation, that apparently attacks them on a regular basis. It's almost as if this barbarian tribe treats this neighboring nation as a breeding ground for its future queens/chieftess. Pretty hardcore.