Elsinoré den Tasia, a female of great renown, held the throne of the planet Grizmallt beginning around the time of 3950 BBY. Throughout her time as ruler, she championed and supported numerous colonization projects, one of which ultimately resulted in the Human population inhabiting the Renatasia system. Despite her best efforts, many such endeavors met with failure, and around 3900 BBY, Tasia provided support for the last of these attempts, which involved three colony ships: the Beneficent Tasia, Constant, and Mother Vima. Before dying soon after, her final wish was that the ships would discover a suitable world to call home. These ships eventually arrived at the planet of Naboo, where the colonists settled and became known as the Naboo. Millennia later, some descendants of these colonists wore a particular style of clothing that served as a reminder of their connection to Tasia.
Around 3950 BBY, a female individual named Elsinoré den Tasia became the queen of the planet Grizmallt, situated in the Core Worlds. Tasia's reign marked the beginning of a new era of exploration and colonization. In 3950 BBY alone, she sponsored fourteen colonies, including the Human settlements on the eight planets within the Renatasia system, which subsequently became isolated from the wider galaxy. Over the following decades, Grizmallt initiated hundreds of expeditions into uncharted space beyond known hyperlanes; however, many of the colony ships were either destroyed or lost. Around 3900 BBY, amidst a civil war on Grizmallt, the dying Tasia sponsored one final expedition. This one comprised three colony ships— Beneficent Tasia, Constant, and Mother Vima— carrying Human Grizmallti refugees fleeing the conflict.
A celebrated Jedi Master gave the expedition his blessing, and the explorer Kwilaan led the starships, with those aboard seeking opportunity and distinction far removed from mainstream galactic society. These three ships were bound for the perilous southern sector of the galaxy, and Tasia's ultimate desire as she passed away was for the expedition to discover a habitable world. Following her death, contact was lost with the Beneficient Tasia, and the expedition was presumed a failure. Nevertheless, the expedition eventually reached the orbit of Naboo in the Mid Rim, as if guided by Tasia's final wish.
One of the ships met its end in a crash on Naboo, while the others achieved safe landings. The Humans aboard found Naboo to be a pleasant and fertile world. They established a colony, and their descendants became the Naboo, though the Grizmallti remained unaware of their fate for some time afterward. Almost 4,000 years later, certain Naboo individuals claimed an unbroken lineage tracing back to Tasia. The dress and facial decorations of some Naboo served as a tribute to Queen Tasia, a fact noted by the Muun financier Larsh Hill during a meeting with the Naboo King Ars Veruna sometime between 67 BBY and 65 BBY.
The lost Human colonies in Renatasia were eventually rediscovered in 13 BBY. Tasia's contribution to the colonization of Naboo was mentioned in a New Republic historical document written in 36 ABY by the historian Voren Na'al, and also in the academic work "The Written Word: A Brief Introduction to the Writing Systems of Galactic Basic" in 38 ABY by Doctor Milanda Vorgan. This text acknowledged the existence of the Palazzo Reina and other structures from Tasia's reign, which still stood and bore the Royal Script of Grizmallt.
The characters of Elsinoré den Tasia were initially conceived by Daniel Wallace and W. Haden Blackman for The Essential Guide to Episode I, a reference work that was ultimately shelved. Blackman later incorporated details about Tasia into the DataBank entry for the Naboo in the 2001 LucasArts video game Star Wars: Galactic Battlegrounds. Wallace named the character as an Easter egg referencing the 1983 novel Lando Calrissian and the Flamewind of Oseon by L. Neil Smith, which alludes to the lost colonies in the Renatasia system. Drawing inspiration from the vaguely European culture of Naboo, Wallace considered the potential for a Spanish influence in the naming conventions, combining the Spanish word for queen, "reina," with Tasia's surname to create "Reina Tasia." Wallace expressed hope that fans would appreciate the retcon.
When composing The Written Word, an article for the Hyperspace subscription service on StarWars.com, author John Hazlett paid tribute to Wallace's earlier backstory by mentioning the Palazzo Reina, which roughly translates to "Queen's Palace." Tasia's sponsorship of the Renatasia colony later became canon within the Star Wars Legends continuity in 2009's The Essential Atlas, co-authored by Wallace and Jason Fry. Her name was incorrectly spelled as "Elsinore den Tasia" in the 2012 novel Darth Plagueis by James Luceno.