A brief Imperial setting history.
300,000 years ago a mysterious race of advanced aliens visited Earth. They took humans as pets/slaves/servants/co-workers, they also uplifted wolves to intelligence and used them as pets/slaves/servants/co-workers.
Some of these humans and uplifted wolves were transported to distant worlds within out galaxy.
The ancient alien race disappeared, leaving evidence of a massive conflict.
Far off in the galaxy on a world called Vland in the year 4717BC on the Earth calendar the Vilani discovered the jump drive and began exploring and colonising. They encountered alien races and other transplanted human races. In 882BC the Vilani began a series of wars that would lead to the foundation of the Imperium in 473AD.
The Vilani Imperium slowly expanded but stagnated technologically.
In 2087AD the jump drive was invented by Earth, in 2096AD humans from Earth run into humans of the Imperium, war follows. A series of interstellar wars last until 2299AD and result in victory for the Terran forces. In 2314AD a Terran human is elevated to the position of Emperor of the Imperium - this is sometimes called the second Imperium or alternatively the Rule of Man. In 2742AD the Rule of Man finally collapses and interstellar trade ceases, an era called the Long Night affects the worlds of the Imperium.
In the year 3868AD on the former Imperial world of Sylea a federation is incorporated which has the economic and technological might to begin expansion and trade with its neighbouring worlds. In 4518AD Cleon is elevated to the position of Emperor of the newly incorporated Imperium, tracing his lineage back through Terran rulers during the RoM right back to the First Imperium. This is year 0 of the Imperium, or Third Imperium.
It is now 1005 as the Imperium denotes time, or 5623AD on the Terran calendar...
The lmperium is a strong interstellar government encompassing 281 subsectors and approximately 11,000 worlds. Approximately 1100 years old, it is the third human empire to control this area, the oldest, and the strongest. Nevertheless, it is under strong pressure from i s neighbouring interstellar governments, and does not have the strength nor the power which it once had.