Listen then, cartographer. This is the first mystery of the casting.
Quatria, the land, her people, is plural. Quatrium. A four-cornered thing. Thus the singularity of the Hypogeum was first bounded, in the time of the Singulones. Point in the center. Point on the edge. Tie a string between. Duogons have their reign. Fixing on the center, keeping the string taught, rotate slowly around the axis, until returned to starting point. Center, edge. Node, anti-node. End, beginning. At once the same but different. That difference is the history of change. Delta. Center, edge, change. By the the bounding ring, the Reign of the Triangulons has commenced.
From center, connect any two non-opposite edges, directly via the straight roads between them. The Triangulon empire was beautiful, brutal, and thankfully brief.
Connect opposite points in pairs, such that four equal sections result. The original Quadrants preceding Quatria. Connect those who are not yet connected. Circle gets a square. Four Quadriums become one Quatria, and the world begins. Again.
This world is centered upon the Mysteries at the heart of those Prior, called in this age the Hypogeum. It is the source of emptiness and longing to which Triangulon poets and their minstrel descendants sung their languorous dirges and dark soliloquies. The Fourth Point, Termination.
Of the quadrants, number prime, second, tertiary and null, so named on the Songboard: the House of Sorrow, House of Wealth, House of Song, and House of Emptiness.
The Capital of the House of Sorrow is lost Ederron, pushed into the sea during the First Age, her children dispersed in the First Diaspora.
The Capital of the House of Wealth is happy, fat Abbadon, Lord of trade with the underworld, whose destruction marks the passing of the Second Age.
The Capital of the House of Song is troubled Temple Mount, where having reached its apogee, Quatrian culture stagnates and tumbles into degradation, and the crumbling of whose foundation as certain Pentarch sailors broach the Bay of Erasure serves the backdrop of our present narrative, and marks the passing of the Third Age.
The Capital of the House of Silence will be the city to come of Ovarion, where the Pentarcs will take up residence a little off the mainland on an island recently ejected from the mists, and build their palace. The Fourth Age.
This is the mystery of the Precession of the Anti-Nodes, and the key to all ages.