The world initially called Gelefil was an agricultural world located between Ingo and Ko Vari, according to planet lore. Within the [Annoo system](/article/annoo_system], it was one of the seven inhabited planets, which were part of fourteen total planets in the Tharin sector of the Outer Rim Territories. The Nimat Corridor, a significant hyperspace route, traversed the system providing access to the planet. The peaceful and long-lived Ret were its original inhabitants. After the Annoo-dat conquered it, the planet's name was changed to Annoo.
Around 322 BBY, the Annoo-dat, hailing from the nearby world of Annoo, abandoned their failing home and seized Gelefil. Over the course of a century, the Ret assimilated Annoo-dat culture, creating a unified civilization where both groups identified as Annoo-dat, and Gelefil became known as Annoo. To differentiate the two species, xenobiologists began using the terms Annoo-dat Blue for the Ret and Annoo-dat Prime for the original Annoo-dat, though this distinction was not used by the Annoo-dat themselves.
The southern continent of Annoo saw extensive industrialization of agriculture, while the northern continent largely retained its original character. The Ret language, Tra'ang'a, was replaced by Dat-an as the common language of all Annoo-dat.
Approximately in 27 BBY, General Ashaar Khorda launched a violent coup, but the Galactic Republic intervened, leading to his defeat and forced him into hiding.
During the early years of the Galactic Empire, the infamous crime lord Sise Fromm established a stronghold on Annoo. From this base, the Fromm Gang schemed to dominate the other major criminal organizations. Simultaneously, Demma Moll and her daughter, Kea, operated a farm complex on the planet and formed a resistance cell to oppose both the Fromms and the Empire.