Vila ultimately did not choose to place her Royal Palace in the deepest part of the Mil Forest.
When the Undead Tribe was building the Magic Great Wall and clearing the forest interior, she traveled throughout the entire forest in her little carriage, finally choosing the turning point connecting to the western Marching Mountains.
The Mil Forest and the Marching Mountains resemble a longbow just set up with an arrow but not yet drawn, and Vila chose the curved part of the bow.
Yet the deepest and densest section of the forest is the upper part of the bow, sandwiched between the Marching Mountains and the Esi River.
That's where the towering trees are most numerous.
But Vila did not choose that place.
Although the depths of the forest are the safest for forest creatures, with the protection of the Undead Tribe, she didn't need to compete with those poor little animals for survival space.