Did the Kurosians also declare war against those that traded with the Litheans? Or was it just one-sided with the Litheans being assholes to Kurosians?
Hay Hibi! ❤️ Naah, the Kuros weren't as uptight with the Litheans. They respected their purpose as their opposites, though their opinion twists the closer to the Fall. Kuros only clashed with Litheans when the dark dragons left the borders of Kurosia to hit back at enemies that have done them wrong, and it almost always makes situations way worse.
When it comes to a Lithean and Kurosian fighting each other one on one, neither can win. Their elements can poison and weaken the other, so direct fighting is often avoided for both party's sake. They'll fight using allies, but the damage their direct wars is almost always greater than any victory. Litheans see this more as a threat than Kuros do, they recognized they weren't meant to fight Litheans while the light dragons saw Kuros as more of a threat for it. Over centuries this builds, until the Fall eventually tips the balance over on the Kuros and the Litheans claim themselves victors over 'darkness'.
It isn't really them that defeats or even causes the Kuros's downfall though, they just took credit 8,)