Thousands of years ago, when they learned that their sun was about to supernova, they constructed a multi-generation ship named Yonada to take them to a new home light-years away. Over the centuries of travel, the Fabrini forgot that they were on a spaceship.
First contact between the Fabrini and the Federation was established in 2268 by Captain James T. Kirk of the USS Enterprise. They helped them understand the true nature of their world and helped them reach their intended destination. (TOS episode: "For the World is Hollow and I Have Touched the Sky", novel Ex Machina)