As it stands, not much is known about the history of the Khaian. It is known that their home planet is Ca'eva, in the Ja'vistis system of the Caii'eva galaxy, adjacent to the Milky Way. They have existed in their homenplanet for the past 500,000 years, although the accuracy of this information is hard to discern. They began space exploration late compared to humanity, but they accelerated in their technology much faster after they began to travel through the skies. 

Apart from this information, anything else about the Khaian history is purely speculation.