“All the Hellenistic States had thus been completely subjected to the protectorate of Rome, and the whole empire of Alexander the Great had fallen to the Roman commonwealth just as if the city had inherited it from his heirs. From all sides kings and ambassadors flocked to Rome to congratulate her; they showed that fawning is never more abject than when kings are in the antechamber…w:Polybius dates from the battle of Pydna the full establishment of the universal empire of Rome. It was in fact the last battle in which a civilized state confronted Rome in the field on a footing of equality with her as a great power; all subsequent struggles were rebellions or wars with peoples beyond the pale of the Romano-Greek civilization -- with barbarians, as they were called. The whole civilized world thenceforth recognized in the Roman senate the supreme tribunal, whose commissions decided in the last resort between kings and nations; and to acquire its language and manners foreign princes and youths of quality resided in Rome. A clear and earnest attempt to get rid of this dominion was in reality made only once -- by the great Mithradates of Pontus. The battle of pydna, moreover, marks the last occasion on which the senate still adhered to the state-maxim that that they should, if possible, hold no possessions and maintain no garrisons beyond the Italian seas, but should keep the numerous states dependent on them in order by a mere political supremacy. The aim aim of their policy was that these states should neither decline into utter weakness and anarchy, as had nevertheless happened in Greece nor emerge out of their half-free position into complete independence, as Macedonia had attempted to do without success. No state was to be allowed to utterly perish, but no one was to be permitted to stand on its own resources… Indications of a change of system, and of an increasing disinclination on the part of Rome to tolerate by its side intermediate states even in such independence as was possible for them, were clearly given in the destruction of the Macedonian monarchy after the battle of Pydna, the more and more frequent and more unavoidable the intervention in the internal affairs of the petty Greek states through their misgovernment, and their political and social anarchy, the disarming of Macedonia, where the Northern forntier at any rate urgently required a defence different from that of mere posts; and, lastly, the introduction of the payment of land-tax to Rome from Macedonia and Illyria, were so many symptoms of the approaching conversion of the client states into subjects of Rome.”

The Changing of the Relationship between Rome and Her Client-States
The History Of Rome, Volume 2. Chapter 10. "The Third Macedonian War" Translated by W.P.Dickson
The History of Rome - Volume 2