The First Imperial Age was the longest dynasty Xi'an history. Spanning almost fifteen thousand Xi'an years, it began with the crowning of the first Emperor Ru'a in MXY I.0 (19668 BCE), several years after the loss of the Xi'an homeworld RyiXy'an (Hyoton III) in 19770 BCE. During this era, the Xi'an discovered jump points, established the Civil Service (Pō't.ōngp.ū), codified the tenets of Li'tova into common law, and first terraformed worlds outside their home planetary system.
The Age came to an end in I.14680 (878 BCE), when Emperor Se'ang se Ru'a, the final heir of his house, stepped down to make way for Y.ah'a se Xy.ō, the oldest daughter of her House and the first Emperor of the Second Age.