It was created when the Humans' inhabited Hoteis after many years of living in the wild. The first thing they did was create the capital building.
They used all the Stone that they could, there hadn't been Iron discovered at this point. Many additions were added to the building years later, Glowstone was added in place of many torches, Iron floors were laid, additonal rooms, and a dungeon.
One of the most influential people to stay in the Capital building of Rinca was Rezser Jonich. During his time in the building he persuaded many government officals to do as he thought would benefit Rinca, and Hoteis. "The Great War" started at the Rinca Capital Building, some parts of the building were destroyed and have been left that way.