They might have really been from The Parting of the Ways since they were impure Daleks.
Not too sure about that, seeing as it was heavily implied that Rose erased every single one of them from existence. There wasn't really much opportunity for any to escape.
Then why would Daleks made from Kelad DNA aka Davros be considered impure since they come from the same source matieral as the pure ones.
Nevertheless, the fact remains, those Daleks cannot have been from the fleet in PotW because Rose destroyed all of them in an instant. And they cannot be from the fleet in The Stolen Earth, because that's been wiped from the timeline.
And as we saw in Flesh and Stone, once a being is absorbed by the time crack, it not only ceases to exist there and then, but its entire timeline leading upto that moment is erased too, so it never existed in the first place. So does this mean Davros never existed now? Bummer.

And now that the Dalek invasion never happened, this would mean that Donna Noble never became the DoctorDonna, and the Meta-Crisis Tenth Doctor never went to live on Pete's World with Rose. Also, correct me if I'm wrong, but wasn't it implied that Dalek Caan had somehow manipulated things so that Donna met the Doctor in the first place? Well, now that Caan never existed, how could they have met?
And on top of all this, we still have the problem of how the Daleks are still around. I really think Moffatt has opened up a gigantic can of worms with this whole time crack business.