Kapitel 550: 8.14.2 Lady lies revelation.

The prestige of Cynark was once brought down multiple levels after their defeat at the hands of a small nation of Yethel. They were mocked and harassed by their neighbors, who considered it a sign of weakness. 

This is why the Mehmet's castle was dragged toward them, as a deterrence. Specifically toward Sumire, considering they were the proxy of Azad on the Brihma Continent. Though the war still broke out, it might be due to the deterrence of the mage castle, but Sumire didn't try to be any audacious in their attacks.

It was closer to harassment, a low-level one where mostly the lower-level soldiers lost their lives, and nothing more.

It was closer to Sumire putting on an act to satisfy their backers. Even with Cynark's defeat at the hands of Yethel, those in the know understood why Cynark suffered such a loss and why the story would be different if on their border.