Alros passed the border of the Torim Kingdom with ease. Then again, with how the Marsh of Torim is great danger to their nation, they will accept any help they could.
After all, Marsh of Torim is not the full Danger Zone, despite being a Level Danger Zone on it's own. It is merely one of the many subsidiaries of another danger zone, the dreaded Dread Swamp.
The Danger Zone in question is one of the few legendary Level 5 Danger Zone, an impossibly powerful Danger Zone that could not be handled by many of the nations that bordered their subsidiaries.
The only reason why the nations remain standing, or at least don't leave the place in terror, is the existence of a Level 5 Nation in the form of the Miurnal Divine Empire. The Empire in question bordered a Level 4 Danger Zone, another subsidiary but this time it is closer to the core of the Dread Swamp.