This picture also gets me thinking...there are plenty of worlds inthat have primitive technology/societies despite the existence of space travel. Some are kept that way so Astartes chapters can recruit from them (the logic being they produce "natural born" warriors), while others are so isolated, strategically useless, and/or possess such harsh environments that no-one has bothered bringing them into the 41st Century. Some of these worlds could very well be about as advanced as Earth was around 1000-1200 AD but with additional sentient species, the Immaterium and individuals capable of wielding it. Thus,andcould technically exist in the same universe.