During the Yinchorri Uprising a decade before the Eeth Koth was a member of one of the three parties sent to the Outer Rim to put down the threat. Master Koth traveled to Yitheeth with Jedi Masters Adi Gallia, Tsui Choi, and her Padawan, Theen Fida. Disguised as technology traders, the group was ambushed shortly after they arrived almost as if the Yinchorri were waiting for them. The attack squad was led by a Devaronian named Olmar Grahrk who they arrested and interrogated for information. Olmar told the Jedi, the Yinchorri headquarters was not located on Yitheeth, so the group left for Yibikkoror where they arrived just in time to save the team of Jedi sent there.
Collecting Jedi Masters Plo Koon, Micah Giiett, Lilit Twoseas, and her Padawan K'Kruhk, the squad departed for Yinchorr where the final Jedi team was under attack from a hoard of Yinchorri soldiers. Following the battle, which resulted in the deaths of Master Twoseas and Theen Fida, Eeth Koth and the Jedi received word from Jedi Master Yaddle at the Jedi Temple of the discovery of a fourth and previously unknown Yinchorri world, Uhanayih. The Yinchorri maintained a subterranean base they used as their headquarters. Eeth Koth and the Jedi traveled to Uhanayih where Jedi Master Saesee Tiin crashed his starship into the base and acquired the Yinchorri's surrender.
In the years leading up to the Clone Wars, the Republic faced a Separatist crisis and the Jedi were forced to respond to hundreds of emergencies that arose throughout the galaxy because of it. Systems were torn apart by civil war, old grudges were re-ignited, and warlords and terrorists sought to take advantage of the opportunity. One such terrorist was Ashaar Khorda, an Annoo-Dat General who sought leadership on Annoo after he led a small rebellion on Annoo. However, the Republic instilled its own ruler before Khorda could take power which drove the General underground where vowed to strike back at the Republic. In order to do this, Khorda sought the ancient relic known as the Infant of Shaa, which was said to contain enough Force-energy to destroy a planet. When the Jedi Council learned of this plan, they were not privy to the target, but they narrowed the possibilities to Coruscant, Alderaan, and Corellia.
At the start of the Clone Wars, Eeth Koth was a member of the two-hundred strong strike team sent to Geonosis to confront Count Dooku and his droid army before war could spread throughout the galaxy. Unfortunately, it would turn out that the Jedi were too late. Scores of Jedi died on Geonosis that day, and the droid army succeeded in repelling the Jedi plunging the galaxy into full scale war. Sadly, Jedi Master Eeth Koth would lie among those who died at Geonosis when his LAAT/i gunship was shot down. Eeth Koth's death would be a part of the Sith's grand revenge which would ultimately result in the destruction of the entire Jedi Order. Following Master Koth's death, he was replaced on the Jedi Council by fellow Zabrak Jedi Master Agen Kolar.