This is still controversial amongst fans. Originally, in The Daleks, it was stated that the pre-Dalek humanoids were called "Dals". In the TV Century 21 comics, the origin of the Daleks was shown in the comic story Genesis of Evil. Here the humanoids were called Dals. The scientist that created them was called Yarvelling. All sources for the next decade confirm this.
However, in the later TV story "Genesis of the Daleks", a totally different story is shown. Here we are told for the first time that the pre-Dalek humanoids are called Kaleds, and that the scientist that created them was a totally different man called Davros. Most sources now subscribe to the Kaleds/Davros version.
No official source has ever commented on the whole Dals/Kaleds or Yarvelling/Davros problems. All we have an are a variety of non-canon fan explanations. These range from "They took place in separate universes" to "the original version was erased by the Time War" to "The Dals and Kaleds were allies who were both fighting the Thals" to a variety of others, some well-thought out, others incoherent and absurd. However, they are all simply fan explanations. There is no official word on what relationship, if any, there is between the Dals and the Kaleds.