Rannians are near perfect matches for humans genetically; however, generations of relying on their advanced technology have caused the Rannian gene pool to weaken. As a result the population became stagnant and sterile. To combat this problem the Rannian scientist Sardath invented the Zeta Beam, an advanced teleportation device in an effort to introduce new bloodlines to the population.
Rannian's as a whole are an intelligent, if not egotistical species. They are accustomed to using fantastic technology such as teleportation, flying cars, plasma weapons, and faster then light starships as routine and everyday facts of life.
Using the beam, Adam Strange was transported to Rann where he fell in love with Sardath's daughter Alanna, and fathered a daughter named Aleea. He has become the most recognizable Rannian, along with his family, and the Green Lantern Vath Sarn.
The Rannians have often come into violent conflict with their galactic neighbors, the Thanagarians. This conflict was only exasperated when, as a means of self preservation, Rann was transported into Thanagar’s Polaris system from its original location in Alpha Centauri.
Over time, outside forces have also fueled the Rann/Thanagar conflict. When Superboy-Prime pushed Thanagar dangerously close to its sun, rendering the planet uninhabitable, Rann was used as a sanctuary for escaping Thanagarians. The crowded planet was a hot bed of xenophobic prejudice and suspicion, felt by many members of both races.
This clash of cultures caused tensions to simmer to a dangerous level on planet. The conflicts were further inflamed by the death worshipers in the Cult of Seven Devils, who manipulated the situation to ignite the first Rann/Thanagar War.
Their planet is destroyed during the Holy War when the Weird is used as a nuclear bomb to destroy the evil Synnar. Thankfully all Rannians were teleported to the now unpopulated Throneworld and together with Prince Gavyn, found New Rann.