Apparently, according to a history book, Cormyr occupied Arabel since Arabel's creation and was ruled by the King of Cormyr as part of Cormyr until the end of the history text, which ends at 1370. It seems to be a few years out of date.
King Azoun is spoken of very highly in the text, as are all nobles and members of the Royal Family, the Purple Dragons and the many Militias of Cormyr, although the book was written during Cormyr's rule of Arabel by a retired Purple Dragon Lionar and might be bias.