Thyferra was a hot, humid planet located in the Polith system on the Rimma Trade Route, on which most of the galaxy's bacta was produced. It was also a major political power as bacta production was an essential commodity.
Thyferra, in the Inner Rim's Polith system at galactic coordinates L-14, and was the homeworld of the Vratix people.
The Vratix had already colonized many celestial bodies in the Polith system when they were in first contact with the Galactic Republic around 4100 BBY.
Since the Vratix had discovered how to create bacta from alazhi and kavam, the planet became an important Republic world, drawing profit-hungry human colonists. The Vratix shared the secret of bacta production with their Human neighbors, who eventually gained control of the bacta industry and hired many of the natives as workers in their bacta plants.
Between 3959 BBY to 3956 BBY, during the Jedi Civil War, the planet had become part of Revan's Sith Empire.
During the Clone Wars, the Third Fleet of the Confederate Navy was based at Thyferra. In 20 BBY, the fleet joined the First Fleet for an attack on the Core Worlds planet Duro.
Eventually, Thyferra was almost completely controlled by two Human-run corporations: Zaltin and Xucphra. These two corporations were chosen by Emperor Palpatine to supply the Empire's bacta, thus eliminating any real competition in the bacta market.
Prior to the Battle of Yavin, Darth Vader led an assault to root out a traitor. At the end, he Force-choked an Imperial commander.
The Rebel Alliance's bacta supply on the planet was a target set by Moff Kohl Seerdon. Around 1 ABY, after setting a diversion on Sullust, he invaded the planet, sending AT-STs and TIE interceptors to prevent Alliance bacta from reaching the group. However, the plot was thwarted by Rogue Squadron, and Seerdon was killed after engaging Luke Skywalker in a dogfight.
Thyferra was liberated by the New Republic in 5 ABY. However, the New Republic didn't settle on the planet which stayed officially neutral in the war. Thyferra was in fact in trouble due to significant tensions between Humans and Vratix and between the Xucphra and Zaltin Corporation.
In 7 ABY, Ysanne Isard backed a coup that saw a pro-Imperial faction taking over Thyferra. The faction later elected her head of state, allowing her to remain in lawful power, eliminate the Zaltin, control the bacta industry, and start a small but important conflict known as the Bacta War. During the Battle of Thyferra, Rogue Squadron and its allies, operating at the time independent from the New Republic—which for political reasons could not directly interfere—liberated Thyferra from the Empire and imperial loyalists using guerilla tactics, pluck, and native allies.
During the Yuuzhan Vong War, the Yuuzhan Vong attempted to poison the planet's bacta supplies. The scheme did not come to fruition.
Thyferra later joined the Killiks in the Swarm War, the New Jedi Order being unable to defend it from a coup orchestrated by the Killiks. Following the end of the war, Thyferra reverted to Alliance control.