Riast was a planet in the Inner Rim, near the Hapes Cluster. From very early on in its human-inhabited history, it followed a custom of discarding all governmental structures every five hundred years and reorganizing the government and to a lesser extent the entire society from the ground up. As a reorganization took place in 31 BBY, two years, in fact, after it had originally been scheduled, the government was still very young at the time of Republic's collapse.
During the first part of Galactic Civil War, the president of Riast was Neri'top'worza'ita'aya. She had harbored Separatist sympathies during the Clone Wars, and as president privately opposed the Empire and quietly allowed her planet to become a refuge for its enemies. In 10 BBY she was caught and executed by Darth Vader, and the planet was put under martial law. She had been popular, and the Riastion population fought savagely against their Imperial occupiers, who were finally driven off almost immediately after the Emperor's death in 4 ABY, after which another reorganization took place.