From Watchtower Port to the Emerald Corridor, plus the Flash Sea, everything above and below the waves has already been included in Leon's dominion... If you have to say, that independent Elf City Danalan of the Zhen Dan Kingdom is like a nail. But even so, Leon has no intention of tearing up the peace treaty.
The Talia Alliance isn't as strong as the Empire, but they do have their own skills. It's best not to provoke them for now.
Next, the Lost Plateau environment is extreme. The side near the desert is at a lower altitude where humans and dwarves live. The side near Watchtower Port has only a few giants, dragons, and monsters, all of which are strange and chaotic entities, easy to conquer but hard to govern, and not worth the cost.
