Eldar

Eldar were the first race in the stars, the first to decode the Runes and markings that made a helm. The first ship , a massive derelict ship crashed on their planet 100000 years ago. The site now is a holy place for any eldar. 

 

The eldar formed the navigators guild, which grew in power and at one time ruled the eldar empire. As more races entered space, the more the navigators guild became its own entity outside the eldar culture. The eldar still reference themselves as the firstborn of space, but have acknowledged that they have lost control of the navigators guild.

Ancients

Little is known about the race that came first. They built the waygates and the giant derelict ships that can be found throughout the galaxy. The design of the ships indicates that they were a large race who did not use legs to traverse their ships. Some scholars believe they could have been serpentine, while others point to the ocuth and their ability to levitate. The state of their ships also indicates that the race most likely met their fate in a war or invasion. There are no known representations of the Ancients, nor any first hand stories or myths.