Arnorian successor states? 3 or more

[IxnaY AintsaY]

Originally Posted by Inziladun

That supposition would seem to be borne out by the fact that they ended before Arthedain.

Maybe. I certainly feel Arthedain was at least stronger than Rhudaur, and -at least- equal to Cardolan, but I haven't been able yet to find a definitive textual support for that feeling. There is though this later note in "The Heirs of Elendil" from two versions of a page in an earlier manuscript than the one I excerpted (Page 209, under "Argeleb I" a king of Arthedain.):

'Slain in battle 1356. Angmar is repulsed but turns upon the lesser kingdoms.' [The replacement page has:] 'Slain in battle with subkingdoms of Cardolan and Rhudaur'.

Bracketed insertion is CT.