During the Early Middle Ages, Italy endured sociopolitical collapse and barbarian invasions, but by the 11th century, numerous rival city-states and maritime republics, mainly in the northern and central regions of Italy, rose to great prosperity through trade, commerce and banking, laying the groundwork for modern capitalism. These mostly independent statelets served as Europe's main trading hubs with Asia and the Near East, often enjoying a greater degree of democracy than the larger feudal monarchies that were consolidating throughout Europe; however, part of central Italy was under the control of the theocraticPapal States, while Southern Italy remained largely feudal until the 19th century, partially as a result of a succession of Byzantine, Arab, Norman, Angevin, Aragonese and other foreign conquests of the region. The Renaissance began in Italy and spread to the rest of Europe, bringing a renewed interest in humanism, science, exploration and art. Italian culture flourished, producing famous scholars, artists and polymaths. During the Middle Ages, Italian explorers discovered new routes to the Far East and the New World, helping to usher in the European Age of Discovery. Nevertheless, Italy's commercial and political power significantly waned with the opening of trade routes that bypassed the Mediterranean. Centuries of rivalry and infighting between the Italian city-states, such as the Italian Wars of the 15th and 16th centuries, left Italy fragmented and susceptible to foreign domination, and it was subsequently conquered, exploited, and further divided by European powers such as France, Spain and Austria.
According to Antiochus of Syracuse, the term Italy was used by the Greeks to initially refer only to the southern portion of the Bruttium peninsula corresponding to the modern province of Reggio and part of the provinces of Catanzaro and Vibo Valentia in southern Italy. Nevertheless, by his time the larger concept of Oenotria and "Italy" had become synonymous and the name also applied to most of Lucania as well. According to Strabo's Geographica, before the expansion of the Roman Republic, the name was used by Greeks to indicate the land between the strait of Messina and the line connecting the gulf of Salerno and gulf of Taranto, corresponding roughly to the current region of Calabria. The Greeks gradually came to apply the name "Italia" to a larger region In addition to the "Greek Italy" in the south, historians have suggested the existence of an "Etruscan Italy" covering variable areas of central Italy.
The borders of Roman Italy, Italia, are better established. Cato's Origines, the first work of history composed in Latin, described Italy as the entire peninsula south of the Alps. According to Cato and several Roman authors, the Alps formed the "walls of Italy". In 264 BC, Roman Italy extended from the Arno and Rubicon rivers of the centre-north to the entire south. The northern area of Cisalpine Gaul was occupied by Rome in the 220s BC and became considered geographically and de facto part of Italy, but remained politically and de jure separated. It was legally merged into the administrative unit of Italy in 42 BC by the triumvir Octavian as a ratification of Caesar's unpublished acts (Acta Caesaris). The islands of Sardinia, Corsica, Sicily and Malta were added to Italy by Diocletian in 292 AD.