All of Sullust was composed of multicolored rock, veined by lava channels; the planet went through atmospheric blackouts caused by gouts of smoke and ash.
The underground of the planet was more stable and habitable and was occupied by the native Sullustans who navigated the tunnels (housing edible lichen gardens and potable water) with an innate sense of direction.
The planet joined the Galactic Republic when Sullustan merchants connected their planet to Tapani sector with the Rimma Trade Route in 5500 BBY.
Sullust was attacked by the Krath during the Great Sith War, but was successfully defended by the Galactic Republic.
The world was volatile with hundreds of active volcanoes, producing a noxious, toxic atmosphere and intense electrical storms. These conditions, combined with the planet's rich mineral deposits, caused the native Sullustan inhabitants to live in underground caves. The underground caves were humid and cool, with a diverse biosphere supported by underground lakes. The planet was once known for its podraces. During the New Sith Wars, the Brotherhood of Darkness captured the planet.
Sullust was the headquarters of the galaxy-spanning SoroSuub Corporation, a member of the Commerce Guild. Nearly one-half of the population was under its employment. As the Old Republic crumbled, the governing Sullustan Council became weak. Under President Beolars Bribbs who was also the Galactic Senator, the planet seceded from the Republic in 22 BBY and joined the Confederacy of Independent Systems. Less than a month later the Republic dispatched a task force to retake the planet, led by Jedi Knight Rees Alrix. The Republic took heavy casualties in the battle due to a treachery in their midst and the planet remained one of the Confederacy's most prized holdings until the end of the Clone Wars.
With the expansion of Palpatine's New Order, SoroSuub assumed leadership of Sullust with Corporate Proclamation 137d and announced its full support of the Empire. In exchange for several lucrative contracts and the promise of guaranteed future business, SoroSuub took a hardline against the Rebel Alliance and its supporters.
Angered at SoroSuub's illegal takeover and support of the Empire, Sullustans formed resistance cells under the leadership of Sian Tevv that became model rebel cells during the Galactic Civil War. Tevv's resistance fighters, combined with a coup to take over SoroSuub by pro-Alliance forces, garnered enough support to wrestle control of Sullust away from SoroSuub shortly before 0 ABY. Several months after the Battle of Yavin, Rogue Squadron launched a strike to destroy a Capacitor.
The Sullustan resistance remained independent from the Alliance, although it allowed the Alliance Fleet to use Sullust as the staging point for planned destruction of the Death Star II, since Sullust was an endpoint of the Sanctuary Pipeline as well as due to a board chairman of SoroSuub being rescued from Imperial detention by Rebel force.
The Alliance also launched a diversionary attack in the system, to draw the Imperial fleet away from Endor.
After the Battle of Endor, Sullust was one of the first worlds to officially align itself with the Alliance of Free Planets, and subsequently the New Republic. It was represented on the New Republic Provisional Council by Sian Tevv and later in the New Republic Senate by Sien Siev and Niuk Niuv. Sullust went on to be a key member of the Galactic Alliance.
In 5 ABY, Superior General Sander Delvardus of the neighboring Eriadu Authority tried to conquer Sullust but he was defeated by Sien Sovv who launched a counterattack campaign that liberated all the Authority.
Darth Krayt's Galactic Empire took control over Sullust after the end of the Sith–Imperial War. SoroSuub was forced to keep at least 80% of its production facilities manufacturing Imperial vessels, most of which were not even of Sorosuub design. Forced into desperation, Sullustans began building secret underground facilities closer to the planet's core. Products created in those facilities were secretly smuggled offworld and sold in open market.