Good summary by the Possum as usual, but it stops a bit short on explaining the more recent phenomenon of the modern nation state that developed as a result of the French and similar revolutions.
Contrary to the warlord like states that cumulated in feudal monarchies, the modern nation state is an evolution of this concept in which the newly formed capitalist elites conspired with the administrative class to get rid of the previous rulers (the warrior class). By sharing some power like that, these elites can stay mostly anonymous and more easily push charismatic but easy to control "leaders" in their stead. The administrative class in return ensures the iron clad rule of private property, as this is ultimately the source of power in a capitalist society.
This symbiotic relationship in the modern nation state between capitalist and administrative interests on the basis of enforcing private property is important to note as it brings out an important point: a feudal state might be able to exist without capitalism, but capitalism can not exist without a state enforcing its basis of power. Hence so called "anarcho-capitalism" being an absurd notion.