The Last Empire
Thousands of years ago, the details already lost to history, the Last Empire was formed. Humanity had discovered how to build portals to link worlds, and began a long, steady campaign to explore and fill the seemingly limitless number of worlds that portals could reach. The Last Empire, usually referred to as simply the Empire, quickly grew to be the pinnacle of human civilization. The organization of the Empire provided the stabilizing force, and when necessary the military might, to help humanity begin to conquer the universe.
Hundreds of worlds, many of which had their own sentient races, were assimilated into the Empire. Over time, the Last Empire matured from simply conquering by brute force, to a more gradual and non-aggressive approach. In recent millenia, the Empire is confident in its supremacy and is willing to take a less aggressive approach, cooperating with the native races and simply waiting for them to choose to join the Empire (most eventually do). As a result, although the Empire is 90% human, a diverse variety of beings make up the rest. To a citizen of the Empire, pointy ears or blue skin are hardly worth notice.
Two hundred years ago, the Empire arrived on Selanis, a small expedition force arriving through a freshly created portal. Their leader, Samus Birchon, established contact with the civilized native races now known as elves and dwarves, and soon learned of their plight: massive invasions of orcs, goblins, and other “chaotic” races threatened their civilizations. An alliance was forged, and the full might of the Empire was put to work dealing with the threat, especially the famous armored and mounted Knights of the Empire. After a successful campaign, the Kingdom of Birchon was formed as a colony of the Last Empire on the “frontier” world of Selanis.
In recent years, the activities of the Empire have been almost completely focused on the war with the Horde. As the war dragged on, the Empire found it necessary to start actively conscripting its citizens, including the ones on Selanis. This conscription effort has only increased over time.
The common currency of the Empire is the Imperial Mark. A massive empire and a few thousand years have made the Mark remarkably stable.