I have understood a kingdom to be one where a central monarchy exercises its direct authority not just over a portion of its people's, but all of them. Hence, the trick is in the very names they used themselves... When you hear the title of King of the "Trinovantes," it is a misnomer: He should actually be called "Chief." Theoretically, once a chief is fortunate enough to another tribe, he would then call himself Chief of "Picts," for example. Eventually, if he is successful enough to the point where there are no rival chiefs, then his status is automatically elevated by the fact that there is no dispute to his authority and, hence, he becomes King.
This is why, along with their political structure, the Aedui should never be considered a kingdom, because they lacked the type of authority over their own people that is typical of a kingdom, as there was always a #2 around, despite their dominance.
As for the "diluted" statement, it may be that my accentuation might have crossed the line of hyperbole, but my intention was to illustrate that Rome's main instrument in conquering others was not its diplomacy but rather its military, as you seemed to suggest:
Carthage, I know for a fact to be a more formidable and more politically-stable opponent (factional politicking aside), and they're people ceased to exist.Rome didn't just possess some all defeating, invincible army of demi-gods..., they worked hard at ensuring that their enemies were ...... diluted. They could only "demolish their enemy to the pulp of extinction" because those enemies were weakened by political infighting, by divisions.
As for Rome's status, to further explain, it too could only really have been considered a kingdom up until it dominated all the native oscan/italian lands (some would argue it would exclude the Po in this time period), although it still would've not been considered one as its political structure was an oligarchy as opposed to a monarchy.
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