Board Thread:Warhammer 40k General Discussion/@comment-90.211.181.229-20130907201722/@comment-6078851-20131204004822

in terms of territory occupied orks control the majority of the milky way, they're everywhere, and if they didn't have the imperium to fight they would control even more territory. you can rest assured that they would seek out the interex. and because the interex don't force worlds to join their side (unlike the imperium, albeit with only humans) they would never have achieved the same scale of empire as the imperium, and as such would never have enough citizenry choosing to fight to be able to field enough soldiers to cope with even a few medium sized waaagh!'s. whereas the citizenry of the imperium have no choice - they fight, they die, they're replaced.

the imperium has 3 major, and telling, advantages over an interex empire, 1) numbers. 2) a psychotically fanatical belief in their unity, and 3) astartes. the imperium is only what it is because of emps - primarchs - and astartes, and the interex had nothing that could compare to astartes in wrath.