Approximately 9,000 years ago, in the Unknown, the plane of Xoriat became coterminous with the plane of Eberron. During that time, the lords of Xoriat, an aberrant race known as the daelkyr, pierced the planar walls and launched an invasion of Eberron, on the continent of Khorvaire. They assaulted the goblinoid Dhakaani Empire, decimating most of western Khorvaire.
The daelkyr lords, masters of shaping reality, found joy in twisting the beings of Eberron to suit their own purpose. One daelkyr, named Belashyrra, the Lord of Eyes, molded the first beholders as his finest masterpiece. The beholders served as artillery in the armies of the daelkyr.
However, the remnants of the Dhakaani Empire and the Gatekeeper druids managed to push the daelkyr and their creatures back to Xoriat, trapping what creatures remained on Eberron beneath the Khyber.
Since then, some beholders have remained among the daelkyr and the Dolgaunt, while others have started their own followings among the Cults of the Dragon Below. A rare few have abandoned the path of aggression for philosophy and reflection. Some choose to live beneath small towns or villages, manipulating events to provide the beholder with power or wealth. Still others continue to look for ways to bring their daelkyr masters back to Eberron.
The recently formed criminal organization House Tarkanan, operating in Sharn, uses the beholder as its symbol.
In 997 YK, the Umbragen came under siege by a daelkyr army, which included beholders.