The Upper Regions are rock, and are at the very top of the mountains. Though it may be hard to believe, all regions are connected by the mountains. Though the rock may be soft under all of the layers of soil, in the Upper Regions it is hard rock on top. It closely relates to igneous, and is used to build the cities of the Rockettacai.
The Rockettacai are very similar to humans in many respects, though they have adapted to life deep within caves. They have black as night skin, with a reflective pink pigment under and around their red eyes. They have a short stock build, and don't grow much higher than 5 feet. They are very vocal, and have male female, and other various genders.
They have learned to use advanced technology to make a synthetic type of farm, where they grow wheat like crops, as well as other vegetables. They have animals as well, closely resembling bats. Their main economy subsists of exploring the caves, and agriculture.
An interesting thing to note is that as they use synthetic fabric for things like pants and shoes and other garments, they use spider web spun strings for shirts.