During the Thousand Year War, Thals were just as brutal as their Kaled enemies. They had no qualms about using the slave labour of Kaled prisoners and Mutos to build the neutronic missile, even when they knew the radiation from the missile would kill the slaves. (TV: Genesis of the Daleks) There were seven males for every female. (AUDIO: Corruption)
Fifty cycles after the First Doctor's first visit to Skaro, the Thals had adapted Dalek technology for their own use in order to lower the radiation level on the planet. However, while there was a dedicated military force on Skaro, many Thals wished to return to pacifism despite some Thals being aware of the possibility of the Daleks' continual survival on other parts of the planet. (AUDIO: Return to Skaro)
Turning full circle, they again adopted a militaristic way of life, though only, it seems, against the Daleks. (TV: Planet of the Daleks) Though dedicated to a militaristic lifestyle, the preservation of their species and lineage was of great importance to the Thal people. Consequently, all members of the Thal military were required to have a child before they were allowed to serve. Although most Thal children grew up without their parents because of this, they were taught to be proud of them because they had fought the Daleks. (PROSE: War of the Daleks) "Sweet life" was a Thal oath. (PROSE: The Dalek Factor)
Thal technology advanced in parallel to that of the Kaleds for some time. The Kaled began researching means of survival while the Thals concentrated on ways to destroy their enemies. They developed the neutronic missile but lacked the power to break down the Kaled defences with it. (TV: Genesis of the Daleks)
Following the Thal-Dalek battle, the Thals reverse engineered the technology of the Dalek City to build the Thal City. They had developed motor vehicles, ones which ran on static electricity, and energy weapons, ones that could, after many concentrated blasts to the dome, destroy a Dalek War Machine. By Tryana's own admission however, the ionising towers were beyond Thal science. As noted by the First Doctor and Ian Chesterton however, their technological base had several anachronisms, the Thals still being reliant on animal-drawn carts for transport outside their city. (AUDIO: Return to Skaro)
After this stage in their history, it was many generations until the Thals developed interplanetary flight. Their ongoing conflict with the Daleks forced them to develop more weaponry. They used compact firearms that were attached to their holsters by a cord. However, these weapons seemed to have no effect upon Daleks.
One account stated the Thals and Dals were descended from humans transplanted from Earth to Skaro as an experiment by the Halldons. (PROSE: We are the Daleks!) Bernice Summerfield was aware that the SSSSSSS had made a few crude wormholes in the fabric of space-time and sent genetic data through them to plant their "seed of Aryan purity" throughout history, resulting in some planets far from Earth having blond-haired, blue-eyed humanoids. (PROSE: Down) 100 million years before the Thousand Year War, the Thals' evolution diverged from that of the Kaleds. (AUDIO: Corruption)
The Thals had written records going back nearly half a million years. Records would describe the Thals as originally a warrior people, while the Dals were more orientated towards philosophy and science. (TV: The Daleks) Because the earlier sections of their recorded history was distilled from oral tradition, they were less accurate than later documentation of Thal history. (PROSE: The Secret Lives of Monsters)
Thousand Year War
Originally, the Thals and Kaleds lived together in peace. (AUDIO: Purity) Due to unknown circumstances, the Kaleds and Thals engaged in the Thousand Year War, (TV: Genesis of the Daleks) with historians finding evidence of both a Thal attack or a preemptive strike by the Kaleds. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe) Though they originally used advanced technology, towards the end of the war they became more primitive. By the end of the conflict, both Thals and Kaleds sheltered in domed cities overlooking a wasteland.
The war concluded when Davros, a Kaled leader, gave the means to destroy the Kaled Dome to the Thals. They used this compound in the missile they sent to the Kaled city and destroyed it. In "retaliation" for the destruction of the dome, Davros ordered the Daleks to destroy the Thals. Led by a Thal, Bettan, Thals and Mutos joined together to fight the Daleks, who were trapped in the Kaled bunker after an explosion, defeated but still alive. (TV: Genesis of the Daleks)
Though heavily weakened, the Thals saw an opportunity to destroy the burgeoning Dalek race by attacking the newly built Dalek City. Fearing an attack, the Daleks responded by detonating a neutron bomb. The Thals retreated to a high plateau, one of the few places on Skaro were vegetation still grew, and over the centuries would come to recall this as a neutronic war. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)
The Thals renounced violence and became pacifist farmers living in small bands on a less radiated plateau. They would not even engage in violence for self-preservation and showed no curiosity about the Dalek City or its inhabitants. The Thals believed that, following the war, radiation had mutated them into perfect beings, though after a stage of advanced mutations.
The Thals relied on a great rain for their crops but after it been overdue for two years, the crops were ruined, forcing the Thals to move to the petrified jungle near the Dalek City, over five hundred years after the war passed, to look for food. Ian Chesterton, a companion of the First Doctor, used moral blackmail to force the Thals, Alydon in particular, into putting together an expedition into the Dalek City to fight against the Daleks who intended genocide against the Thals. The Thals invaded the Dalek City, cut off the power and so deprived the Daleks of the static electricity they needed to live. (TV: The Daleks)
Another group of Thals led by Themis had instead sought to take shelter in the ruins of the Thal Dome. After braving Skaro's mutated wildlife, the Thals made it to the Dome only to find it inhabited by a group of Daleks who promptly exterminated them. (COMIC: Safe Haven)
Following what would become known as the Thal-Dalek battle, the Thals, through reverse engineering Dalek technology, constructed a new city for themselves. As their technology developed, a movement of Thals began championing for a return to their pacifist roots. On one of their scientific excursions to the Dalek City, their leader scientist, Tryana, discovered the Dalek City's secret incubation level and the slumbering form of the Dalek Supreme who duped her into thinking that it desired peace. 50 cycles after the battle, the Doctor and his companions returned to Skaro, their arrival causing the Dalek Supreme to abandon its ruse, leading a resurrected army of Daleks to invade the Thal City. The Doctor and his friends managed to rally the Thals against the Daleks once again before they took their leave, though some Thals worried that the Daleks might return once again, possibly having another colony on the planet. (AUDIO: Return to Skaro)
By the 26th century, the Doctor's first visit to Skaro was considered a legend.
In 2540, the Third Doctor and Jo Grant met a taskforce of Thals on Spiridon where a small group, led by Taron, had landed to destroy a Dalek army massed on that planet. The Thals had, by then, reclaimed Skaro. They had only recently developed spaceflight. The mission to Spiridon was the furthest they had ever gone. Earth was unknown to them, believed to be simply part of the Doctor legend. (TV: Planet of the Daleks)
The Thals were eventually forced off Skaro by the Daleks, theorised by the Time Lords to have sought refuge in a series of off-world colonies. (PROSE: Dalek Combat Training Manual) They were eventually said to have 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)
In reality, a decoy world named Antalin had 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)
Eight centuries after the Daleks had been defeated, the Thals had made it their mission to hunt and destroy any remaining Daleks in the galaxy. A squad of Thals travelled to a planet in the Quadrille and discovered that the Doctor was unwittingly working for the Dalek Emperor. Whilst the Thals believed that the Doctor had helped them to escape, they had in fact been infested with the Dalek factor, which, after several generations, would turn the Thals into Daleks. (PROSE: The Dalek Factor)
Last Great Time War and beyond
Thals from the period of the Thal-Dalek battle, (TV: The Daleks) being pacifists, refused to give the Time Lords information on the anti-radiation drug during the Last Great Time War. Aware that later Thals were willing to fight, the Time Lords nonetheless remained interested in establishing an alliance with such experienced Dalek fighters, (PROSE: Dalek Combat Training Manual) a wish that was eventually fulfilled. However, by the time Thals actively fought alongside the Time Lords, they resented the Time Lords' attitude towards them as they'd been fighting Daleks in their own right throughout their history and believed the Time Lords were just as guilty as the Daleks of altering Thal timelines. At this time, the Thals were still settled on New Davius. The War Doctor helped design a new warship to give to the Thals, named the Temmosus, though its commander nearly gave it to the Daleks in a failed attempt to form a truce to give the Thals a break from fighting. (AUDIO: Temmosus)
The Thals existed on Skaro (PROSE: Postcards from the Universe) after it had been recreated by the Daleks after the Time War. (TV: The Witch's Familiar) Missy's pet Slyther, nicknamed Doctor, ate several of them, angering the other Thals. (PROSE: Postcards from the Universe)
In an alternate timeline, the Thal scientist Professor Ptolem was part of a Dalek effort to find a cure to the Mutant Phase. This timeline was averted when the Fifth Doctor convinced the Dalek Emperor not to give the Daleks of the past an ineffective pesticide that would cause the Mutant Phase in the first place. (AUDIO: The Mutant Phase)
During the Last Great Time War, the War Master acquired the Anti-Genesis codes from Gallifrey. Travelling back to the Thousand Year War, he ensured that Davros was killed by the bomb that should have crippled him, (AUDIO: From the Flames) usurping the Kaled's placed as creator of the Daleks. Twenty years following this, he ordered his Dalek Supreme to detonate a neutron bomb to render the Thal race extinct. (AUDIO: Shockwave)
In the Unbound Universe, the Thals shared Skaro with the Kaleds before their tensions were escalated into open war when the Quatch attacked Skaro. Like in N-Space, the Kaleds of this reality were turned into Daleks by Davros. The Daleks quickly conquered Skaro and enforced a police state on the Thals in preparation for the return of the Quatch. When the Doctor and Alistair Gordon Lethbridge-Stewart arrived on Skaro, they helped the Daleks and Thals defeat the Quatch with Alistair choosing to remain with the hope of one day bringing about a permanent peace between Daleks and Thals. (AUDIO: Masters of War)
In one reality, Skaro was home to the Thals and Kaleds. Early in its history, this Skaro was attacked by this reality's Time Lords who sought to destroy the Kaleds. This act instead unified the Kaleds and Thals against the Time Lords who were recorded as being destroyed by the Skarosian species. A peaceful world, this Skaro never experienced the Thousand Year War. Following the Daleks of N-Space being wiped out in the Last Great Time War, the Dalek Time Strategist arrived on this Skaro and manipulated its Davros to help resurrect the Daleks. As he became more like his multiversal counterparts, Davros ordered his new Daleks to attack Skaro's Thal districts as tests of their abilities. (AUDIO: Palindrome)
In the Warrior's universe, the Doctor had destroyed the incubation chamber during the Genesis Incident but failed to recover his Time Ring. When the alien technology was discovered by the Kaleds, they joined forces with the Thals and the already active Daleks into the Unified Skaroan Alliance. (AUDIO: Dust Devil, Aftershocks)
Behind the scenes
The Discontinuity Guide states that, in the original timeline where Davros was killed by the Daleks he created, the Thals contemptuously refered to the Kaleds who survived his slaughter as "Dalek people" or Dals. The Thals then ended the Thousand Year War by detonating a neutron bomb resulting in destruction so great that the Daleks were forced to flee the planet in a hastily constructed spacecraft whilst the Thals themselves were affected by the radiation, committing themselves to pacifism as a result. More primitive Daleks, the early products of Davros' experimental program, remained in the Dalek City before being wiped out in the Thal-Dalek battle 500 years later. The advanced Daleks then returned to make Skaro their home until the Dalek Civil War forced them to depart once again, leaving the Thals in peace before they developed space travel, fighting the Daleks in the Spiridon campaign. Eventually, at some point between the years 3500 and 4000, the Daleks returned to Skaro once again and wiped out the Thals who lived there. The Fourth Doctor's interference in the creation of the Daleks created a new timeline in which Davros survived. It is conjectured that, in this timeline, the Daleks either exterminated the Thals when they left their bunker or noted with disinterest that they had already gone.