The Black Era is part of Platarious long history. It started once the Clone War was won and Unick took control of the planet. He used the fear the population had of the droid facories to turn the planet to fear his power. The Black Era was a depression for the people of Platarious. The rich ruled over the poor, if someone was in with Unick you were rich and powerful and if you were just a common citizen you were very poor. Along with Unick's control he was the only one who was allowed a name, the rest of the people were given numbers. Unick even erased the planets name to show that he was superior to even the planet. (The original name of the Platarious was forgotten over time).
The Black Era ended when Bastilla came to this planet and over threw Unick from power, and gave it to the people, who then voted her as ruler of the planet.