Sky Islands had strictly defined altitude ranges.
Different heights required different materials, energy cores, and outer structures.
On the European continent, the vast majority of land-dwellers lived in small villages or small towns, all built within mountain ranges or halfway up mountains. This was because Sky Islands kept falling, crashing endlessly to the ground. Through countless failures, Europe's Witches created Sky Islands capable of "safely floating and moving," and determined suitable flight altitudes in increments of every "one hundred and fifty meters."
Then, with modifications from Olivia and Eileen, two rare geniuses of the Witch world, the Witch world finally came to possess Sky Islands like these.
The East had been far luckier. The Witches of the Eastern world—of an unnamed country—had inherited the legacy of another great nation that was inconvenient to name. Without making enormous sacrifices, they obtained experience manuals for building Sky Islands, as well as complete construction manuals. Later, they even used this foundation to invent superior Sky Island structures, capable of being built at heights exceeding eleven thousand meters.
Of course, they had merely mastered the method. Building a Sky Island at eleven thousand meters required nearly more than five times the resources needed for one at ordinary altitudes.
Better materials, more intricate rune arrays, higher-processing arcane cores, finer designs, and... more expensive outer walls and temperature simulation systems.
For Witches, even if low-altitude Sky Islands did not activate temperature simulation or air shields, they could endure it. At high altitudes, however, failing to activate them would make a Witch drowsy and send her into a state of semi-hibernation... Want to kill a Witch? Ha. Even without a life-support system, drifting through space, they could evolve the ability to survive without oxygen and turn into stone, until they crashed into another planet with life and