I'm basically just a wee bit confused with the institution of monarchy as a whole, from the sociological and anthropological aspect.
I've always assumed that most monarchs ruled over a territory or settlement (i.e. very state-like). However, the more I research, the more I encounter the idea that most monarchs in fact ruled over nations rather than territories. Of course, the realities might have varied, but I'm looking at the ideal of how these monarchs rationalised and justified their powers.
For example, Napoleon was Emperor of the French; not Emperor of France. Albert I was King of the Belgians, not King of Belgium. Alfred the Great was King of the West Saxons (and later, King of the Angles and the Saxons/Anglo-saxons).
So this means that said Monarchs ruled over the nation/people, rather that the territory that had clear boundaries. I assume this made sense, since at the time, states didn't have set territories; therefore, a monarch held power as far as he could enforce (even if an Englishman was living in France, he was still technically a subject of the English King).
But then, we have the city-state monarchs. Was Hadrian Emperor of the Romans? Or Emperor of Rome?
So I'm a bit confused. Did we used to have heads-of-state ruling nations, then shifted to territories when the world began to adopt of the Westphalian state model with its set boundaries? Or have heads-of-state always been either one or the other, with most societies were either ruled by territory or by nationhood?
I feel like you maybe be getting a bit confused about the semantics here. Monarchs rule territory as long as that territory is controlled by them. When we examine feudal monarchies like Alfred the Great, like you mentioned only controlled Wessex and the borders of Wessex was determined by how far the lords (aldermen) loyal to him held land. An alderman who bears no loyalty to Wessex who borders Wessex, whether he be Saxon or what have you would not recognise Alfred as his king solely on the basis that Alfred was proclaimed king of the Saxons.
The alternative to this is kings who claim to hold territories that they do no several English and later British kings and queens claimed to be king/queen of France while having no provinces in France whatsoever.
Napoleon was Emperor of France, Albert was king of Belgium and Alfred was King of Wessex. Nationhood evolves from held territories. Hadrian could also hardly be called a monarch of a city state however considering he held a large, multi-cultural empire. Simply because we call it the Roman Empire, does not mean it is a city state.
The King or Emperor "of the [people]" was a 19th century piece of rhetoric that didn't have a common legal connotation.
Napoleon's "Empire" was a legal and political novelty created to give him a basis for rule despite having no blood claim to the historical throne of France. It was quite odd for him to retain that formulation when he ultimately did establish a multi-national empire full of non-Frenchmen.
The formulation "Emperor of the Germnans" was chosen at German unification both to make clear that there was a personal and national connection between Emperor and subjects (as opposed to the intermediated relationship of the Holy Roman Emperor with his German subjects), while also preserving the dignity of the monarchs of the constituent states of the German empire, who remained "King of Bavaria", "Duke of Saxe-Coburg-Gotha," etc.
The "King of the Belgians" thing I suppose (but don't know for a fact, apologies) was an effort to forge a nationlike sense of unity out of French, Dutch and German speaking Belgians who then (as now) often felt very alienated from each other.