The Crown of Aragon (; , , , ) was a composite monarchy, also nowadays referred to as a confederation of individual polities or kingdoms ruled by one king with a personal and dynastic union of the Kingdom of Aragon and the County of Barcelona. At the height of its power in the 14th and 15th centuries, the Crown of Aragon was a thalassocracy (a state with primarily maritime realms) controlling a large portion of present-day eastern Spain, parts of what is now southern France, and a Mediterranean "empire" which included the Balearic Islands, Sicily, Corsica, Sardinia, Malta, Southern Italy (from 1442) and parts of Greece (until 1388). The component realms of the Crown were not united politically except at the level of the king, who ruled over each autonomous polity according to its own laws, raising funds under each tax structure, dealing separately with each Corts or Cortes. Put in contemporary terms, it has sometimes been considered that the different lands of the Crown of Aragon (mainly the Kingdom of Aragon, the Principality of Catalonia and the Kingdom of Valencia) functioned more as a confederation than as a single kingdom. In this sense, the larger Crown of Aragon must not be confused with one of its constituent parts, the Kingdom of Aragon, from which it takes its name.