An advanced version of this civilization might think of the Earth as uninhabitable: how would you power anything without a builtin planet-scale, locally operable gradient?
At first armies can march in one direction of the ring or the other, with every natural defense point being sort of a Thermopilae situation
Then, technology progresses and certain machines may allow smaller groups to traverse outward for limited periods of time. Analogous to our submarines?
Would then flight make the world "flat" and globalized?
They can't lay cables across the scorching dor icy deserts, so worldwide comm must either follow the ring or be satellite-based
