Mustafar the Planet

Mustafar is an outer rim planet, the planet is covered by hundreds of volcanic caldera, most of which are in a state of constant eruption. The volcanic activity is caused by gravitational stresses on the planet created by the two gas giants that affect its orbit (similarly to Jupiter's Galilean moons). An automated energy and mineral collection facility are located on the planet.
Despite its hellish conditions, Mustafar has developed native lifeforms. A sentient race, known as Mustafarians, developed in the cooler hollows of the planet. They are divided into two subspecies: the tall, thin Northern Mustafarians (led by the enigmatic "Maverick Main") and the shorter, hardier Southern Mustafarians (aka "The Mustafar Rats"). The Techno Union took an interest in the planet and the mineral-rich molten rivers covering its surface, and employed the Mustafarians to mine these minerals. The Mustafarians made use of native "lava fleas", as well as the Techno Union's technology that gave them further protection from the heat. The natives had little interest in offworld politics and were content to work on their homeworld.