Precisely. Cartels don't require a government to exist, and the absence of government letting them beat you and kill you and take your stuff makes them easier to entrench. Some of these cartels may even claim land as theirs and exact payments from those under their "protection". We might call them "barons", say, and their henchmen "knights". And these strongmen might, due to relative imbalance of force, have to swear fealty to "counts" and "dukes" and "kings", and whoa I think I just had the weirdest dream, that ancap is an undisguised pathway to corporatist feudalism. Weird.

Any ruling order, whether it be a government or something else, requires at least the tacit consent of the majority. I believe it would be much more difficult to take over an area lacking a strong centralized government as opposed to an area with one. Militaristic efforts in Afghanistan being a prime modern example.