The Atoan people originated from the Atoan system and were considered a Near-Human species possessing sentience.
Although the external appearance of Atoans was similar to that of standard Humans, their internal physiology differed significantly; rather than one central heart, Atoans had thousands of smaller hearts distributed throughout their bodies, from their extremities to their core. This unique anatomy granted them greater speed and strength than humans, but also increased their vulnerability to blood loss. Like Humans, Atoans also possessed lungs, a sternum, and a cranial cavity.
The planet Atoa, located within the Atoan system, served as the homeworld for the Atoan people. By the year 19 BBY, the newly established Empire had limited information regarding their culture and society.
In the year 19 BBY, Garoche Tarkin abandoned his allegiance to the Empire and sought refuge on Atoa. This decision was driven, in part, by his deep-seated aversion to the atrocities he was forced to commit in the name of Palpatine. He then assisted the Atoans in their insurgency, alongside Lady Saro, the High Priestess of Atoa. Their relationship evolved into a romantic one, resulting in Saro's pregnancy. Captain Shale also defected, seeking to assassinate Lord Vader, but his attempt was unsuccessful. Shale later reappeared with Saro and attempted to persuade Vader to repent for his actions. Vader ultimately killed them both in an attempted suicide by collapsing the cathedral they were in as atonement for his sins as Vader. However, he survived, and blamed Garoche's death on the Atoan Insurgents, as part of a plan with the Emperor to deepen Wilhuff Tarkin's hatred of any form of insurgency and make him a better tool of the Empire.
As Palpatine predicted, the death of Garoche motivated his father to commit genocide against the Atoans as retribution for their perceived involvement in his demise.
Atoan society was governed by a theocracy, with High Priestesses serving as the leading figures. Their religious beliefs centered around the Twenty-nine Atoan gods.
Despite sharing the same sector of space as Umbara, the Atoans communicated using their native language instead of Galactic Basic Standard. This language proved to be indecipherable, even for protocol droids. The shaman Lady Saro acquired the ability to speak Basic by consuming the tongue of a deceased stormtrooper.
The Atoans were a technologically advanced species, possessing blasters, starfighters, and floating cities situated on a tar-pit planet.