The Dragon Lords built a civilization during the Bolsenian Era that stretched across Xytegenia and encompassed the surrounding islands. The nature of the Dragon Lords (even whether they were human or dragon) is unknown.
The Dragon Lords used Dragon Magic, thought to be the powerful precursor to magic used in the "modern" era. There are hints, many of which are contained in the Palace of the Dead, that they were largely evil. The presence of a Gate to the Abyss in the Palace, the presence of Dragon Lord ruins on top of another Gate in the Hanging Gardens, and their evil tendencies are all strong indications that they were part of the forces of evil during the Ogre Battle, and their civilization vanished following the conclusion of the Ogre Battle.