The original inhabitants of Sicily, long absorbed into the population, were tribes known to Greek writers as the Elymians, the Sicani and the Siculi or Sicels. Of these, the last were clearly the latest to arrive on this land and were related to other Italic peoples of southern Italy, such as the Italoi of Calabria, the Oenotrians, Chones, and Leuterni (or Leutarni), the Opicans, and the Ausones. It's possible, however, that the Sicani were originally an Iberian tribe. The Elymi, too, may have distant origins outside of Italy, in the Aegean Sea area. Sicily was colonized by Phoenicians and Punic settlers from Carthage and by Greeks, starting in the 8th Century BCE. The most important colony was established at Syracuse in 734 BCE. Other important Greek colonies were Gela, Acragas, Selinunte, Himera, and Zancle or Messene (modern-day Messina, not to be confused with the ancient city of Messene in Messenia, Greece).

These city states were an important part of classical Greek civilization, which included Sicily as part of Magna Graecia - both Empedocles and Archimedes were from Sicily. Sicilian politics was intertwined with politics in Greece itself, leading Athens, for example, to mount the disastrous Sicilian Expedition during the Peloponnesian War.

The Greeks came into conflict with the Punic trading communities with ties to Carthage, which was on the African mainland, not far from the southwest corner of the region, and had its own colonies on Sicily. Palermo was a Carthaginian city, founded in the 8th century BCE, named Zis or Sis ("Panormos" to the Greeks). Hundreds of Phoenician and Carthaginian grave sites have been found in necropolis over a large area of Palermo, now built over, south of the Norman palace, where the Norman kings had a vast park. In the far west, Lilybaeum (now Marsala) never was thoroughly Hellenized. In the First and Second Sicilian Wars, Carthage was in control of all but the eastern part of Sicily, which was dominated by Syracuse.

In 415 BCE, Syracuse became an object of Athenian imperialism as exemplified in the disastrous events of the Sicilian Expedition, which reignited the cooling Peloponnesian War. In the 3rd century BCE the Messanan Crisis motivated the intervention of the Roman Republic into Sicilian affairs, and led to the First Punic War between Rome and Carthage. By the end of war (242 BCE) all Sicily was in Roman hands, becoming Rome's first province outside of the Italian peninsula.

The initial success of the Carthaginians during the Second Punic War encouraged many of the Sicilian cities to revolt against Roman rule. Rome sent troops to put down the rebellions (it was during the siege of Syracuse that Archimedes was killed).

Carthage briefly took control of parts of Sicily, but in the end was driven off. Many Carthaginian sympathizers were killed-- in 210 BCE the Roman consul M. Valerian told the Roman Senate that "no Carthaginian remains in Sicily".

For the next 6 centuries, Sicily was a province of the Roman Empire. It was something of a rural backwater, important chiefly for its grainfields, which were a mainstay of the food supply of the city of Rome.

The empire did not make much effort to Romanize the region, which remained largely Greek. The most notable event of this period was the notorious misgovernment of Verres, as recorded by Cicero in 70 BCE, in his oration, In Verrem.

In 440 CE Sicily fell to the Vandal king Geiseric. A few decades later, it came into Ostrogothic hands, where it remained until it was conquered by the Byzantine general Belisarius in 535. But a new Ostrogoth king, Totila, drove down the Italian peninsula and then plundered and conquered Sicily in 550.

Totila, in turn, was defeated and killed by the Byzantine general, Narses, in 552. For a brief period (662-668), during Byzantine rule, Syracuse was the imperial capital, until Constans II was assassinated.

Sicily was then ruled by the Byzantine Empire until the Muslim Arab conquest of 827-902. It is reported in contemporary accounts that Sicilians spoke Greek or Italo-Greek dialects until at least the 10th century, and in some regions for several more centuries.

The cultural diversity and religious tolerance of the period of Muslim rule under the Kalbid dynasty made Palermo the capital city of the Emirate of Sicily. This continued under the Normans who conquered Sicily in 1060-1090 (raising its status to that of a kingdom in 1130). During this period, Sicily became one of the wealthiest states in Europe, and according to historian John Julius Norwich, Palermo under the Normans became wealthier than the England of its day. After only a century, however, the Norman Hauteville dynasty died out and the south German (Swabian) Hohenstaufen dynasty ruled starting in 1194, adopting Palermo as its principal seat from 1220. But local Christian-Muslim conflicts fueled by the Crusades were escalating during this later period, and in 1224, Frederick II, grandson of Roger II, expelled the last remaining Arabs from Sicily. Conflict between the Hohenstaufen house and the Papacy led in 1266 to Sicily's conquest by Charles I, duke of Anjou: opposition to French officialdom and taxation led in 1282 to insurrection (the Sicilian Vespers) and successful invasion by king Peter III of Aragón.

The resulting War of the Sicilian Vespers lasted until the peace of Caltabellotta in 1302. Sicily was ruled as an independent kingdom by relatives of the kings of Aragon until 1409 and then as part of the Crown of Aragon.

Ruled from 1479 by the kings of Spain, Sicily suffered a ferocious outbreak of plague (1656), followed by a damaging earthquake in the east of the region (1693). Bad periods of rule by the crown of Savoy (1713-1720) and then the Austrian Habsburgs gave way to union (1734) with the Bourbon-ruled kingdom of Naples as the kingdom of the Two Sicilies.

Sicily was the scene of major revolutionary movements in 1820 and 1848 against Bourbon denial of constitutional government. The 1848 revolution resulted in a sixteen month period of independence from the Bourbons before its armed forces took back control of the island on 15 May 1849.

In late 1852, Prince Emanuele Realmuto had set up power in North Central Sicily. Highly educated, the prince established a political system set to bring Sicily's economy to the highest levels in all of Italy.

The Prince's life however was shortened by an assassination in 1857. To this day some of his work is still present in the Italian parliament. Sicily was joined with the other Italian regions in 1860 following the invasion of irregular troops leaded by Giuseppe Garibaldi and the resultant so called Risorgimento.

In 1866, Palermo revolted against Italy. The city was soon bombed by the Italian navy, which disembarked on September 22 under the command of Raffaele Cadorna. Italian soldiers summarily executed the civilian insurgents, and took possession once again of the island.

A long extensive guerrilla campaign against the unionists (1861-1871) took place throughout southern Italy, and in Sicily, inducing the Italian governments to a ferocious military repression. Ruled under martial law for many years Sicily (and southern Italy) was ravaged by the Italian army that summarily executed hundreds of thousands of people, made tens of thousands prisoners, destroyed villages, and deported people.

The Sicilian economy collapsed, leading to an unprecedented wave of emigration. In 1894 labour agitation through the radical Fasci dei lavoratori led again to the imposition of martial law.

The organised crime networks commonly known as the mafia extended their influence in the late 19th century (and many of its operatives also emigrated to other countries, particularly the United States); partly suppressed under the Fascist regime beginning in the 1920s, they recovered following the World War II Allied invasion of Sicily.

An autonomous region from 1946, Sicily benefited to some extent from the partial Italian land reform of 1950-1962 and special funding from the Cassa per il Mezzogiorno, the Italian government's indemnification Fund for the South (1950-1984). Sicily returned to the headlines in 1992, however, when the assassination of two anti-mafia magistrates, Giovanni Falcone and Paolo Borsellino triggered a general upheaval in Italian political life.