[@Frengo] Most new regiments come from a single planet, whereas the older ones will usually be made up of the remnants of lots of nearly destroyed regiments that are all rolled into 1. Conscripts are ALWAYS from the local area, because the Imperium will just go around the area and say "right, all men that can hold a gun, congratulations, you're now in the Military. Take this armour, this gun and try to kill those things over there. You'll know the enemy because most of them have more teeth than the entire Osmand family."