In the Unbound Universe, the Thals were one of the Skaro's sentient races.
Once the Thals were a warrior race who dominated the planet and used the Kaleds as slaves for their expansion, leading to tension between the two races. These tensions were inflamed by the Quatch whose attack led to the Kaled-Thal War. During this conflict, the Kaled Davros briefly defected to the Thals before he created the Daleks from the mutated forms of the Kaleds. This first batch of Daleks, which later came to be known as the Renegades, destroyed the Thal civilisation before they left Skaro.
Centuries later, the Thals, reduced to a farmer state of being, sought out the Dalek City for new sources of food only for the Daleks to remain hostile. The Thals were aided by the Doctor who led them in the Great Siege, overthrowing the Daleks. After the Doctor had left though, a group of Daleks returned to Skaro from space. As these Daleks were of Davros' second generation, they were not genocidal and imposed a police state on the Thals, the Daleks placing them all in the Thal City. Worthy Thals were taken from the city to be converted into Daleks.
When the Doctor returned to Skaro, he and Alistair Gordon Lethbridge-Stewart helped the Thals ferment chaos in Dalek society before Davros and the Quatch landed. Faced with a common enemy, the Doctor and Lethbridge-Stewart convinced the Thals and Daleks to ally to save their world. After the defeat of the Quatch, Lethbridge-Stewart noted that tensions still existed between the Thals and the Daleks, opting to stay behind to act as a neutral mediator and bring peace to Skaro. (AUDIO: Masters of War)