Sema' s home planet was a planet in the outer edge of the Beta Quadrant. Most of it's surface is covered by lava and has an environment similar to a Class D planet. One of the few species able to survive in this environment are a type of dragon-like animal native to the planet. However, in the mountainous regions of the planet the environment is equivalent to a Class M planet allowing for habitation by humanoids. (Dragon Ball Z vs. Star Trek: The Beginning of Infinity)
In the year 290, a dictator gained control over the planet by manipulating the inscriptions of ancient tombs on the planet and forced every inhabitant off world to return. This era would come to be known as the "first catastrophe". Following the demise of this dictator, a tomb guardian caste was created to prevent future manipulations at the inscriptions in the tombs. The members of this caste were forbidden to leave the planet.
In the year 1750, the Klingons attacked the planet to acquire an energy generator located under a mountain cathedral on the planet. Due to the attack the planet became a world of ruins and the atmospheric poison filters were badly damaged. This caused a number of crises, such as civil wars, that decimated the population of the planet. This incident was later called the "second catastrophe."