Asteroid Belt

The Asteroid belt is a thriving area, filled with thousands of habitats. Most of them are small mining outposts, a community of ~100 managing a small area of space with 20-30 asteroids, but there are around 100 communities with more than 1,000,000 people, and 6 with more than 10,000,000. There is very little major political power in the belt, while the total population nears that of the Gas Giant Coalition, it is fractured and divided like Earth. With no governing body, different bodies align themselves with different planets and theologies. Generally, the asteroid belt is more extreme politically than the major powers, and there are some very strange communities, but as they control large populations and areas of space, the powers see it beneficial to cozy up to them. In general, The People's Democratic Republic of Mars is most popular in the belt, though the GGC has it's supporters, a fair few remain supportive of the United Nations and a minority chose to go it alone or in small confederacies. Roughly, it hovers around a 40/35/25/10 split respectively, shifting as the dance of interplanetary politics ducks and weaves.
Most of the Asteroid Belt Communities are comprised of number of O'Neill Cylinders, implanted deep within a reasonably large asteroid, and counter-rotating to one another. Typically, they will have a small defensive drone fleet, a couple of dedicated hauler ships, and a panic button to whatever larger power they align with.
The insides of the On'Neill cylinders are massively varied, more so even than the landscapes of earth. They range from completely submerged, to entirely arid, from 0 to 1.7 g, from pre-cambrian sludge to highly tech-optimized lifeforms.

Geography

Bunch of rocks

Fauna & Flora

Nothing natural, artificially everything you can think of

Natural Resources

Lots of easily accessible metals, carbonites, silicates, water and basically anything else you can think of.

Type

Asteroid belt

Location under

Solar System