On the planet of Ambria, an incident unfolded in 990 BBY, highlighted by a brief lightsaber duel. This confrontation involved Darovit, a former Jedi Padawan who had not succeeded in his training, and a team consisting of fourteen Jedi. Darovit had previously located his cousin, the Sith apprentice Darth Zannah, on the planet Coruscant. She was there, operating secretly as a Jedi. Fearing exposure, Zannah escorted Darovit to her Master, the Dark Lord of the Sith Darth Bane, on the planet Tython. Subsequently, a group of Jedi pursued them and engaged Zannah and Bane in a duel. Although the Jedi were killed, Bane sustained critical injuries. Following this encounter, Zannah transported Bane to Ambria to seek the aid of the healer Caleb. Caleb refused to provide healing to the dying Dark Lord unless Zannah agreed to surrender her Master to the Jedi Order. Zannah consented to Caleb's terms and informed the Jedi that a Sith Lord was still alive.
However, Zannah betrayed Caleb, murdering him after he fulfilled his part of the agreement. She then employed Sith magic to drive Darovit into insanity and armed him with a gold-bladed lightsaber. When a group of six Jedi Masters and eight Jedi Knights, led by Master Tho'natu, arrived on Ambria with the intention of capturing the Sith Lord, they were ambushed by the deranged Darovit. Mistaking him for the Dark Lord, the Jedi swiftly defeated him. Erroneously believing that the Sith had been eradicated from the galaxy, the Jedi departed the planet, inadvertently allowing Bane's Order of the Sith Lords to endure. For almost a millennium, the Sith remained concealed from the Jedi, until they ultimately revealed their presence with sufficient power to take over the galaxy.
In 990 BBY, Darovit—a Padawan who failed as a Jedi but was redeemed from the Sith—journeyed to the Jedi Temple on Coruscant, the capital planet of the galactic Republic. His objective was to expose the existence of two Sith Lords who had survived the New Sith Wars. However, before he could reveal this information, he encountered his cousin, Darth Zannah, a Sith apprentice, who was disguised as Nalia Adollu, a Padawan stationed on the planet Polus since 995 BBY. Fearing her exposure, Zannah fled, taking Darovit with her to meet her Master, Darth Bane, the Dark Lord of the Sith, on the planet Tython. Nevertheless, a group of five Jedi, commanded by Jedi Lord Valenthyne Farfalla, tracked down the Sith and engaged Zannah and Bane in a duel.
Although the Jedi were slaughtered, Bane's armor, composed of parasitic orbalisks, was compromised when he expelled Force lightning, killing some of them. The orbalisks released lethal toxins into his body for which no antidote was known. Zannah transported Bane and Darovit aboard the starship Loranda to the planet Ambria, seeking the assistance of the healer Caleb, who had previously saved Bane's life ten years earlier during the New Sith Wars. However, Caleb had only healed Bane because the Sith Lord had threatened his daughter. Fearing Bane's return and potential threat to her again, Caleb had sent his daughter away, forcing her to relocate and change her name to avoid being tracked down; Caleb himself was unaware of her location. Caleb resisted Zannah's attempts to torture him into compliance, and Darovit suggested that Caleb might heal Bane if Zannah summoned the Jedi to arrest her Master.
Caleb agreed to the proposition, but Zannah hesitated, as she had much more to learn from her Master. Turning him over to the Jedi meant the likely loss of many Sith secrets he had not yet shared. Conversely, not sending the message would certainly result in Bane's death and the loss of those secrets. Darovit urged her to save Bane's life, join the Jedi upon their arrival, and renounce the dark side of the Force. Ultimately, recognizing she had no other choice, Zannah accepted the plan. She dispatched a message drone to the Jedi, and Caleb proceeded to heal Bane, who eventually regained consciousness. When Zannah informed her still-weakened Master of her actions, he expressed his anger and insisted she kill him rather than allow him to be captured by the Jedi. However, Zannah had devised a different plan—she murdered Caleb, desecrated his corpse, and used her skills in Sith magic to drive Darovit to insanity. She then provided Darovit with Farfalla's gold-bladed lightsaber with the intention of having him attack the Jedi upon their arrival.
Zannah concealed herself and her Master within a small trapdoor inside Caleb's hut and hid their presences in the Force to prevent the Jedi from sensing them. Meanwhile, a team composed of six Jedi Masters and eight Jedi Knights, led by Jedi Master Tho'natu, arrived on Ambria aboard the Jedi cruiser Light of Truth to apprehend the Sith. The Jedi quickly discovered Caleb's dismembered body outside his dwelling. Approaching the hut, Tho'natu announced their arrival and intention to assist the Sith. Darovit then emerged, screaming and wielding the golden lightsaber of the recently deceased Farfalla. He attacked Tho'natu and the other Jedi, who fell upon him and killed him within seconds.
Remembering that Farfalla had wielded a golden lightsaber, Tho'natu concluded that Darovit was the Sith Lord responsible for the deaths of the Jedi on Tython. Noticing Darovit's missing hand, he also presumed that Darovit had been severely injured and sought Caleb's assistance. Tho'natu further deduced that Caleb had sent the message to the Jedi shortly after Darovit's arrival, but Darovit had discovered this and, after being healed, had killed Caleb in retaliation. The Jedi, mistakenly believing they had finally eliminated the last of the Sith, transported Caleb's remains to Coruscant for burial and left the Loranda for junkers. Zannah and Bane escaped a few days later in the starship, and Bane expressed his approval of Zannah's actions.
The Jedi Order commemorated the five Jedi who died on Tython by engraving their names and images on a white stone block, embedding their lightsaber hilts within it, and Caleb was also honored on the list. Jedi Master Obba, a member of Tho'natu's strike team who had become a member of the Council of First Knowledge by 980 BBY, recounted the events of the confrontation to Princess Serra of Doan, who was Caleb's daughter. Upon hearing the Jedi's description of the insane man they had killed, Serra became convinced that the Jedi had been deceived—she remembered Bane's appearance from her childhood and believed he had survived. She then hired an assassin, the Huntress, to hunt down and capture Bane. However, Bane escaped and recruited the Huntress as his Sith apprentice; she subsequently killed Serra.
Zannah's actions allowed Darth Bane's Order of the Sith Lords to remain hidden from the Jedi for nearly a millennium—from 990 BBY to 32 BBY—enabling them to grow in power until they were capable of confronting the galaxy once more. In 19 BBY, the Sith successfully eradicated the Jedi Order and established the first Galactic Empire.
Author Drew Karpyshyn created the confrontation for his 2007 novel, Darth Bane: Rule of Two. The event served to present the deaths of Caleb and Darovit, two established characters. Karpyshyn also used the event to explain the Jedi Order's belief that the Sith were extinct, as depicted in Star Wars: Episode I The Phantom Menace. The confrontation was later mentioned in Darth Bane: Dynasty of Evil, the sequel to Rule of Two and the final book in Karpyshyn's Darth Bane Trilogy. In the novel, Caleb's daughter is told of the events of the confrontation from the perspective of the Jedi.