Medusas originated somewhere in Khyber, though there are conflicting stories of their actual origin. In 778 YK, a clan of medusas emerged from Khyber in Droaam and settled the ruined city of Cazhaak Draal. They are humanoid in appearance, resembling scaled humans with serpentine features, and a mane of serpents in place of hair. On average, they are more intelligent than humans, and perhaps their most well known trait is their petrifying gaze. Any creature that makes eye contact with a medusa is turned to stone, including their allies. As a result of this, a medusa will never make eye contact with someone that they don't wish to petrify, they will avert their gaze or wear some form of eye covering. This doesn't hinder them too much, as they can also see through the eyes of their serpents.
The medusas of Cazhaak Draal are a spiritual people, and many of Droaam's priests and spiritual leaders are medusas, particularly priests of The Shadow. The current leader of Cazhaak Draal, Sheshka, the Queen of Stone, is believed to be blessed by the Shadow. Her title is not a hereditary one, and it is not a statement of nobility, but of fact. Sheshka is the Queen of Stone, she has a stronger natural affinity for stone than any other medusa. This is similar to the Keeper of the Flame within the Church of the Silver Flame, and if Sheshka were to die, her people would search for another medusa blessed by the Shadow to fill her role. Cazhaak Draal is as much a theocracy as it is a monarchy.
The petrifying gaze of a medusa is powerful, but most medusas don't think of it as a deadly weapon. Someone who has been petrified can be restored. The medusas of Cazhaak Draal often use petrification as a way to save mortally wounded or sick medusas, and to preserve them until such a time as they can be treated. Similarly, many medusas choose to be petrified in their old age rather than die, and Cazhaak Draal contains great halls filled with the stone remnants of respected individuals. When a medusa looks at a statue, they don't see death, they see the life that it represents.
History
Medusa have never been a numerous, or widespread, people. Their myths generally tell stories of nomadic wandering, with periodic attempts to create permanent settlements. These attempts always seem to end in disaster, with the medusas being forced to abandon them.These periods of wandering and fleeting settlement came to an end when the medusas settled a Dhakaani ruin deep below the surface. They named this city Niaanu Draal, and it was in this place that they wrote down their myths and established the traditions and beliefs that they still hold today. They remained in Niaanu Draal for over two hundred years before the cycle repeated itself, and they were forced to abandon their homes. The forces of a Daelkyr rose up from Khyber and assaulted the city, and the medusas couldn't hold them back.
For whatever reason, the minions of the daelkyr didn't, or couldn't, follow the medusas to the surface, and so they came to Cazhaak Draal and claimed it as the latest in a long line of new homes.
The Cazhaak Creed, the name of the religious tradition practiced by the medusas, asserts that the Sovereign Host created, and cultivated, weak, powerless creatures that they could easily dominate and control, like humans. They believe that it was The Shadow that created what humans call "monsters" and gave them their supernatural gifts.
The Cazhaak myths maintain that their ancestors were enslaved by an entity they refer to as the "Stone Tyrant", and that the Shadow gave them their powers and inspired them to break free from their oppression and claim freedom. The Gatekeepers believe that it was most likely the Daelkyr Orlassk that created the medusas, blending humanoids with basilisks.
Regardless of which of these stories is true, the medusas are a relatively young species. They resemble humans more than they resemble goblinoids or dwarves, and their first recorded appearance on the surface of Khorvaire was when they emerged to claim Cazhaak Draal, just 220 years ago. It's entirely possible that, as a species, the medusas are only a little over a thousand years old.
The medusas were content with their little city-state for most of the last 220 years. They spent that time renovating it, restoring the buildings to a glory they may never have had originally, and domesticating the dangerous creatures found there. Cazhaak Draal was far larger than they needed for the size of their population, and they had little interest in the outside world.
That was, until 985 YK, when a mysterious visitor came to speak to the Queen of Stone. The visitor, a gray-robed hag, met the gaze of the medusas without fear, and without being affected. Sora Teraza was granted an audience with Queen Sheshka, and they spoke from sunrise to sunset, and then the hag left. The next day, Queen Sheshka told her people to prepare for a great change. She carefully picked individuals from amongst her people and formed a corps of medusas for service in foreign lands. Envoys, diplomats, and spies. When the Daughters of Sora Kell assumed power in 986 YK and formed the nation of Droaam, these medusas were dispatched to the Great Crag. Medusa architects direct and oversee the ongoing construction of the Droaamite cities, and medusas hold many of the positions of power both within Droaam and also within "monstrous" communities throughout Khorvaire.