The stretch of wild forests around Crescent City once were only known as its lands. The border was tenuous to its neighbors' reach but the backing of the Fionan Empire gave it more say in a longer reach.
Even so, there were no real resources or beast clans living around them that would interest Immortals. Lower realms could thrive anywhere in the Celestial Fields, but Immortals only cared about Immortal level resources.
Thus the forests were left to those that wish to trailblaze on their own. Tributes were still required to the city but in exchange they could get protection from bandits or beast tides.
That all changed when a Ruin plopped down in the empty stretch of plains in the forest. Immortals cared nothing for who they trampled trying to get at a Divine Ruin!