Rakk

Rakk was a combination of Rayy and Rann that was destroyed after a meteor impact, causing the planet to separate. There were two colonies on Rakk who resided on each hemisphere. The majority of the planet's crust is stone, below that is water and lava which are divided from each other by a large obsidian barrier. The planet's core is a molten and covered by obsidian.

Pre-Impact
Rakk originally had flourishing life from both hemispheres. Most life was separated into two colonies on the red (Rayy) and blue (Rann) side. The red side depends on the blue for crops in exchange for defense, while the blue side depends on defense in exchange for crops. There was mostly peace between the colonies, only having two major wars.

Post-Impact
After the impact, Rakk was divided into Rakk and Rayy. The colony on Rayy fell quickly due to the lack of tools, seeds, and water needed to grow crop. Rann's side was able to survive a somewhat longer time than the people of Rayy, but was eventually eradicated due to creatures and raiders.

Trivia

 * Rakk sounds like rock which could be what this planet is named after due to its stone crust.