Background: The first 40K book I bought was the 2nd Edition Tyranid codex. I found it fascinating to read through, and I promptly began building an imaginary world at war with itself, something of a combination campaign backdrop/army collection guide.

Parthia IV: A non-specialized world, able to sustain itself. Only a few urban centers, and one Hive-like city with its base carved into a mountain range that is the system capital. Intra-system cargo haulers transported goods and people to the other planets of Parthia.

Parthia I: According to ancient records, early Parthians mined this world heavily. Its current population is small: just a few million fierce and resilient descendants of the mining colony and a cloister of Tech Priests that study and maintain the machines regulating the environment within the tunnels.

Parthia II: A giant orbital station serves as system-wide trade hub. The planet below was once inhabited by an advanced Xenos race; they built the space station above as well as many marvels on the surface. Parthia II was also the first world colonized in the system by humanity. Now it exists primarily as a penal colony, with one heavily defended Imperial outpost on the surface. Outside its control zone is the equivalent of a post-apocalyptic wasteland. Generations of prisoners have organized themselves into anything ranging from nomadic tribes to city states, with some even trading with the Imperial outpost.