For centuries, Sicily, an island in the Mediterranean Sea between North Africa and the Italian mainland, was ruled by a long line of foreign invaders, including the Phoenicians, Romans, Arabs, French and Spanish. The residents of this small island formed groups to protect themselves from the often-hostile occupying forces, as well as from other regional groups of Sicilians. These groups, which later became known as clans or families, developed their own system for justice and retribution, carrying out their actions in secret. By the 19th century, small private armies known as “mafie” took advantage of the frequently violent, chaotic conditions in Sicily and extorted protection money from landowners. From this history, the Sicilian Mafia emerged as a collection of criminal clans or families.

Although its precise origins are unknown, the term Mafia came from a Sicilian-Arabic slang expression that means “acting as a protector against the arrogance of the powerful,” according to Selwyn Raab, author of “Five Families: The Rise, Decline, and Resurgence of America’s Most Powerful Mafia Empires. Raab notes that until the 19th century, the word “mafioso” did not refer to someone who was a criminal, but rather a person who was suspicious of central authority. In the 1860s, a play called “I Mafiusi della Vicaria” (“Heroes of the Penitentiary”), about a group of inmates at a Sicilian prison who maintained their own hierarchy and rituals, toured Italy and helped popularize the term Mafia in the Italian language.

In 1861, Sicily became a province of recently unified Italy. However, chaos and crime reigned across the island as the fledgling Italian government tried to establish itself. In the 1870s, Roman officials even asked Sicilian Mafia clans to help them by going after dangerous, independent criminal bands; in exchange, officials would look the other way as the Mafia continued its protection shakedowns of landowners. The government believed this arrangement would be temporary, lasting just long enough for Rome to gain control; instead, the Mafia clans expanded their criminal activities and further entrenched themselves in Sicilian politics and the economy. The Mafia became adept at political corruption and intimidated people to vote for certain candidates, who were in turn beholden to the Mafia. Even the Catholic Church was involved with Mafia clans during this period, according to Raab, who notes that the church relied on Mafiosi to monitor its massive property holdings in Sicily and keep tenant farmers in line.

In order to further strengthen themselves, Sicilian clans began conducting initiation ceremonies in which new members pledged secret oaths of loyalty. Of chief importance to the clans was omerta, an all-important code of conduct reflecting the ancient Sicilian belief that a person should never go to government authorities to seek justice for a crime and never cooperate with authorities investigating any wrongdoing.

The Mafia’s influence in Sicily grew until the 1920s, when Prime Minister Benito Mussolini came to power and launched a brutal crackdown on mobsters, who he viewed as a threat to his Fascist regime. However, in the 1950s, the Mafia rose again when mob-backed construction companies dominated the post-World War II building boom in Sicily. Over the next few decades, the Sicilian Mafia flourished, expanding its criminal empire and becoming, by the 1970s, a major player in international narcotics trafficking.

The American Mafia, a separate entity from the Mafia in Sicily, came to power in the 1920s Prohibition era after the success of Italian-American neighborhood gangs in the booming bootleg liquor business. By the 1950s, the Mafia (also known as Cosa Nostra, Italian for “Our Thing”) had become the preeminent organized-crime network in the United States and was involved in a range of underworld activities, from loan-sharking to prostitution, while also infiltrating labor unions and legitimate industries such as construction and New York’s garment industry. Like the Sicilian Mafia, American Mafia families were able to maintain their secrecy and success because of their code of omerta, as well as their ability to bribe and intimidate public officials, business leaders, witnesses and juries.

For these reasons, law-enforcement agencies were largely ineffective at stopping the Mafia during the first part of the 20th century. However, during the 1980s and 1990s, prosecutors in America and Italy began successfully employing tough anti-racketeering laws to convict top-ranking mobsters. Additionally, some Mafiosi, in order to avoid long prison terms, began breaking the once-sacred code of omerta and testified against fellow mob members. By the start of the 21st century, after hundreds of high-profile arrests over the course of several decades, the Mafia appeared to be weakened in both countries; however, it was not eliminated completely and remains in business today.