Lost Sollo, Valley of Monsters
In the age before the rise of the mortal races, at the end of the war between giants and dragons, the great giant civilizations sealed themselves into the Valley of Sollo, north of the Silver Range Mountains. The wards over that land stood for the entirety of mortal civilization, never to be breached. The sealed lands, called Lost Sollo, were the subject of speculation and mystery. No one, not even the gods, knew what the giants were doing behind their seals.
On the Day of Dispelling, the wards fell and the mystery of Lost Sollo stood revealed. The giants of the valley were long dead. Lost Sollo was a valley full of ruins and gargantuan monsters unknown by the rest of the world. In a panic and already at war with the Far Realm, the mages and wizards quickly built their own wards and walls around the Valley of Monsters.
As a semblance of order returned in recent decades, the attention of the world has returned to Lost Sollo.