[Mandos]

alas, i disagree with some of these things, Arnor perished because of its own inner turmoils and the multiple assaults upon it by the realm of agmar.however, as you say isildur and anarion were co-kings, their thrones were set side by side in the city of osgiliath. Isildur's was the tower of the rising moon, and Anarion's was the tower of
the Setting Sun.To that effent Ithilien couldnt be called a princedom since it wasnt ruled by a prince, but a co'king. so for loss of a better word, i called it a kingdom.