The great empire of Sætar Rúllur collapsed when their grand portal network collapsed in on itself wreaking destruction across all of northern Útgarðar. Their western capital Öxithorpe became home to a chaotic mess of portals that lets in anything from the outer planes while their eastern capital Svanthorpe imploded creating Mt. Drekafjall in northern Galtarland.
This event is now used to mark calendars with Before Fall of Sætar (BFS) and After Fall of Sætar (AFS) being standard date markers. For convenience sake all of year zero before the Fall is considered BFS.