User blog comment:Supahbadmarine/Canon Policy Discussion 2:Empire and Xenos/@comment-4851119-20131108203019/@comment-4851119-20131110160748

I have an idea: maybe EITHER they have to have a small forward base area in the 40K galaxy that they have trouble getting resources to from their original empire, OR they're migrating from an empire that fell and came across this galaxy by chance, OR they're just arriving in the end of M41, as things get increasingly grim for all sides, and are thus only making things more grim by their arrival.

See my reasoning? Any of these methods avoid OP-ness to different extents