City states are the norm since there’s no high speed travel or communications. I haven’t gotten into too much of that YET but the largest entity is probably an empire based in Argyre, which is still only slightly more centralised than the Hellenic Kingdoms. Both consist of prosperous cities on glaciers and benefit from aerothermal energy. Doesn’t stop bickering and infighting tho, everyone always wants more. Valles Marineris is another spot where I might put larger entities, especially at the mouth where there are a lot of crater lakes, channels, and low land.