First Imperium or Grand Empire of Stars a.k.a the Ziru Sirka (-4045 to -2204).
The first major interstellar civilization, politically and culturally dominated by humans originating on Vland (Vland 1717). The jump drive was discovered on Vland in -9235. Immediately the Vilani
discovered a number of interfertile and technologically primitive human
races on worlds within 60 parsecs. These were gradually brought to a
high-technology state with Vilani help and assimilated into a loose
interstellar community bound by trade and common culture.
Eventually, the client races themselves explored beyond the local
sphere, contacting and trading with still more races. These new races
gained their technology without being assimilated into Vilani culture;
the resulting increased friction eventually resulted in a series of wars
beginning in about -5400.
In response to the threat, Vland began tightening its control of
its trade sphere, and finally organizing it into a centralized state in -5273.
This marked the beginnings of the First Imperium, although there was as
yet no emperor. During the thousand year period of the Consolidation Wars,
Vland conquered and absorbed its enemies until there were no longer any
civilized states on its borders (except for a portion of the Vargr Extents, isolated from the Imperium by the Windhorn rift).
The last war ended in -4045,
and the Vilani declared the establishment of an interstellar empire to
govern all Vilani territory. Known as the Grand Empire of Stars or Ziru Sirka, Vilani dating begins at this point. With no exterior threats, the Ziru Sirka
lasted for nearly 1800 years; at its height, which was attained soon
after the end of the wars, the First Imperium contained 27 sectors and
over 15,000 worlds.
However, the cost of maintaining centralized control over this
vast expanse was cultural rigidity; exploration had ceased with the
beginning of the wars; now scientific research slowed to a halt, and the
beginnings of a hereditary caste system began to emerge. Civilization
was in decline.
As long as there was no exterior threat, the Grand Empire was
safe; but gradually, despite all efforts, technology leaked across the
borders. New interstellar states arose, and the Imperium could no longer
afford to absorb them. Gradually, the Imperium lost territory along its
coreward and trailing marches. Then, in -2422,
the Imperium was contacted along its rimward border by the Terrans, who
had recently emerged into space. Terran expansionism led to a series of
interstellar wars, which ultimately resulted in Terran conquest of the Imperium in -2204 and the founding of the Rule of Man.