The Deep Core, sometimes referred to as the Core of the Galaxy, was a brightly lit region of the galaxy that lay at its very heart. Despite the presence of important city-worlds such as Troithe and Empress Teta, much of the Deep Core was a thinly populated and densely packed mass of stars and planets, dangerous to navigate and largely left alone by galactic explorers. At its center existed the Galactic Centre, an ancient, supermassive black hole that bound the galaxy together. Traveling towards the Core and away from the galactic rim was referred to as going "coreward."
Troithe, an ecumenopolis world in the Deep Core's Cerberon system, was once considered a rival to Coruscant as the cosmopolitan jewel of the Galactic Republic. However, its location in the Deep Core made it ill-positioned for the Republic's expansion into the Colonies and the Inner Rim, causing the world's decline as an industrial powerhouse in the Republic.
The Deep Core
Some Jedi scholars made the case that the Deep Core planet Tython was the site of the Jedi Order's first temple.
By the fifth year of Emperor Sheev Palpatine's reign, the Galactic Empire controlled a part of that region referred to as the Deep Core Security Zone. Kren Blista-Vanee, a member of Palpatine's Imperial Ruling Council, had been instrumental to the creation of hyperspace routes into the star systems of the Deep Core. It was considered a sensitive region and access to the zone was restricted by the 15th Deep Core Reserve Fleet, operating out of nearby Empress Teta. During the Battle of Scarif, Rebel Alliance member Jyn Erso mentioned a data tape labelled as "Deep Core Cartography" while searching for the Death Star's plans in the Galactic Empire's data vault on Scarif.
Following the Battle of Yavin, Luke Skywalker and Nakari Kelen traveled to the Deep Core moon of Fex to investigate a biological research ship belonging to Kelen Biolabs that had suddenly gone silent.
During the Galactic Civil War, the archaeologist Doctor Chelli Lona Aphra led Darth Vader to Tython's Meridional Ice Cap in an attempt to prevent the Sith Lord from uncovering the true location of the Rebel Alliance's base on Hoth.
The Deep Core region originates in Legends continuity and first appeared in the comic Star Wars: Dark Empire, which ran from 1991 to 1992. It became part of canon when it was mentioned in the 2014 novel Tarkin.
In the game Star Wars: Jedi Challenges, the Deep Core is referred to as the Core of the Galaxy. The game describes it as a mysterious place in the center of the galaxy, where a challenge awaited those who ventured there.
- LEGO Star Wars: The Freemaker Adventures — "Escape from Coruscant"