Skaro City Dalek

The Skaro City Daleks were the faction of Daleks who inhabited the Dalek City and were defeated by the Thals in the Thal-Dalek battle. (TV: The Daleks)

Origin
By one account, whilst the first Daleks created by Davros remained entombed beneath the Kaled Dome, the mutated survivors of the Kaled race following the neutronic war retreated to the Dalek City where they found the remnants of Davros's experiments, the vacant Mark II Travel Machines. As the now Dalek creatures came to inhabit these Travel Machines, they became the city-dwelling Daleks. (PROSE: The History of the Daleks)

Behind the scenes

 * According to The Discontinuity Guide, the Skaro City Daleks were early products of the experimental program conducted by the late Davros and had been left behind on Skaro whilst more advanced Daleks had taken to space. These primitive Daleks were all wiped out in the battle with the Thals, though the advanced Daleks would later return to make their home on Skaro, preceding the Dalek Civil War which took place somewhere between the 19th century and the mid-22nd century. It is further noted that, since the Fourth Doctor inadvertently changed Dalek history so that Davros survived, this event would have occurred vastly differently if it happened at all in the new timeline.
 * The Skaro City Daleks were named in issue 19 of Doctor Who: Figurine Collection.