The reason Matthew was aware of the other's existence wasn't because he dispatched spies or scouts into the Dark Forest.
The Wood Elves, who always wanted to conceal the situation, voluntarily exposed it to him.
The unlucky Wood Elves were in urgent need of these supplies, and in collecting various magical plants and magical creature materials, they inevitably brought out some unique things.
Pieces of Devil's Thorn!
These fragments were mostly deactivated and wouldn't cause corruption or impact.
And precisely because of this, while the Wood Elves were cleaning up, it wasn't so easily detected.
Matthew merely needed to "look" over once to easily find the small items with unusual energy reactions.
Even more interesting, Matthew knew about the "existence" of the Devil's Thorn and understood how troublesome it was.
Mainly because the Devil's Thorn was one of the culprits in the destruction of the Kael Elf Kingdom.
