Alliance of Mages
The Alliance of Mages was a pre-Alliance organization of wizard-kings that governed the lands of what is now the Agras and Lowland Plains regions, as well as the Stormreaver Range. The existence of this alliance explains why these areas remained free of Marcon control, while the Marcon Alliance controlled essentially the entire rest of the continent.
The Alliance of Mages may in fact be entirely fictional, as no written account of it can be found before A.Y. 1322. It is believed the AOM was invented by romance writers of the Golden Age. The leading theory is that a now-unknown author created it, and other writers added to the legend by placing the AOM in fan-fictions. A common practice around the early-to-mid Golden Age was to write purely fictional works (often romance novels) set during the Mage Wars and release them as true accounts of history.
This practice would go on to contribute very heavily to the confusion, centuries later, as fictional works made it into the archives of various organizations, and finally into the hands of historians who did not know their provenance.