Removal of the Thals

At some stage in the Daleks' timeline, the Daleks oversaw the removal of the Thals from their respective home planet of Skaro.

History
Whilst considering the development of time technology, the Daleks' immediate concern was the removal of the Thals from Skaro. Although they had no sentimental attachment to their home planet, the Daleks were unwilling to allow the Thals to remain established there, knowing that they would form a second front to attack them. The Dalek Prime deemed that the simplest solution was the mass bombing of the planet, rendering it lethal. As before, the Thals learned of this plan by monitoring Dalek communications. Knowing they had no chance at all of stopping the Dalek attack, the Thals resolved to abandon Skaro again. To prevent the Daleks from realising that they had escaped, a small number of Thal troops remained behind to stage a fairly convincing defense of Skaro in what was effectively a suicide mission, buying time for their people to retreat and consolidate before fighting the Daleks another day. The small band of volunteers fought long and hard, but ultimately fell to the massed Dalek firepower. The Daleks dropped several neutron bombs on the Thal settlements, not realising they were already abandoned. (PROSE: The History of the Daleks)

Indeed, the Time Lords understood that Thals were eventually forced off Skaro by the Daleks, theorising that they had sought refuge in a series of off-world colonies. (PROSE: Dalek Combat Training Manual)

Aftermath
The Thals eventually relocated to another homeworld New Davius, (AUDIO: Brotherhood of the Daleks) some time before the Imperial-Renegade Dalek Civil War, (COMIC: Emperor of the Daleks!) although they occasionally returned to Skaro for brief visits. (AUDIO: Scorched Earth)

In their absence, Skaro was believed to have been destroyed, (TV: Remembrance of the Daleks) though according to the account of the Dalek Prime in actuality a decoy world named Antalin had actually been destroyed. The Thals survived past Antalin's destruction and fought the Daleks on Terakis and wiped out half of the Dalek Eighth Fleet. (PROSE: War of the Daleks)

Whilst still residing on New Davius, the Thals allied with the Time Lords to fight against the Daleks in the Last Great Time War. (AUDIO: Temmosus)