Brief History Lesson:
OK - I hate to do geeky/nerdy on you, but it's what I do best.
First of all, remember that the
Nazgul first appeared over 1000 years before the sinking of
Numenor - which rules out Ar-Pharzon and anyone else around that time. The
Dwarves did not establish
Erebor until about 2000 years into
the Third Age - over 3000 years after the Wraiths appeared and over 3500 years after
Sauron gave the rings to Dwarves and
Men. I don't recall right now whether or not
Dale was established before Erebor, or whether we're told.
I'm sure there were many other
kingdoms to choose from. I think it most probable that Sauron gave the rings to Men who were
kings already. There could have been many forgotten kingdoms on the lands that are familiar to us in their configurations of 5000 years later.
We are told that three of
the nine were
Numenoreans of noble birth. I know some who take that so far as to think that a King of Numenor WAS ensnared, although I disagree with it. For interest's sake though, one particular version of the theory is that it was Tar-Ciryatan - for he would have been old enough to receive a ring (and could have accompanied his father, Tar-Minastir) - and that he actually slew and replaced his son and also ruled Numenor in his son's stead as Tar-Atanamir. Then - once he fully became a Wraith, he drifted off to
Mordor and was followed by Tar-Ancalimon. Sounds far-fetched I know, but get this: Tar-Atanamir dies in 2221 SA, according to "The Line of
Elros" in UT. In LOTR Appendix B, the
Ringwraiths first appear in 2221 SA. 'Coincidence?' my friends will ask. The App B account also shows Tar-Atanamir taking the scepter in 2221, but as I understand it, that was an error on JRRT's part, according to his son Christopher. Hmmm... 'Freudian slip' on JRRT's part?... was he just thinking 'successor to Tar-Ciryatan'??
Anyway - as I said, I'm not at all convinced. I think there would have been plenty of
Numenorean nobles ruling part of
Middle Earth as governors of Numenor - and acting as nominal 'kings' in their areas of control. (note - no 'aftermath of flood' because again, the Wraiths appeared over 1000 years before it) Very possibly some royal cousins or nephews, but I doubt a King of Numenor. Still, there's 2221...
I also think that at the time the Wraiths appeared, it might have been evident who those Wraiths had been. However, that knowledge was either lost to time (and the destruction to follow - who knows, Sauron might have had them wipe out their old kingdoms early on) - or else not revealed to the
halfling chroniclers who passed along to us the information we have.
Thorondor is right about the HoME account. I do not possess that book, but as I understand it from other discussions, it sounds like there was an earlier concept that
Tolkien had of the Ring-Wraiths. Something like that they had all been part of an order of
Wizards - were all or mostly Numenorean - and that
Gandalf was one of them, but betrayed them by turning 'good'. In that version, Gandalf was a Man of Numenor, not a
Maia. Is that essentially correct, Thorondor?