As recorded in His Majesty’s Starship, the dying race native to the Roving, known only as The Ones Who Command, sought a new race to be the masters of their genetically engineered servants, the First Breed (a.k.a. the Rusties). In the initial stages of their search for a replacement race, exploration ships from the Roving came to a nearby solar system. They found signs of life on two planets there, which they dubbed Sample World 4 and Sample World 5. Sample World 4 had a technology equivalent to Earth at the end of the twenty-first century; Sample World 5, a mineral-poor planet, was locked into a perpetual advanced Stone Age.

In an act of calculated xenocide, the beings on Sample World 4 used long range missiles and, ultimately, crewed spaceships to wipe out the race on Sample World 5. The Ones Who Command decided not to invite the beings of Sample World 4 to be their replacements and instead concentrated their efforts on another race — a race of bipeds that called themselves human beings.

Ever since then a hidden space station called SkySpy, carved into an asteroid, has covertly surveyed the creatures, waiting for the moment when they might learn how to leave their solar system and descend on other worlds.

Events did not turn out entirely as the Ones Who Command foresaw, and the result was a new republic, the Commonwealth, based on the Roving and in which humans and First Breed were equal.

SkySpy, at first crewed purely by First Breed, is now crewed by a mixed complement of First Breed and humans. The latter dub the beings of Sample World the Xenocides, shortened to the XCs.

3 June 2153
The XCs attack SkySpy.  Read Chapter 1 of The Xenocide Mission.