Triad (organized crime) in the context of "Mong Kok"

Organized crime refers to transnational, national, or local groups of centralized enterprises that engage in illegal activities, most commonly for profit. While organized crime is generally considered a form of illegal business, some criminal organizations, such as terrorist groups, rebel groups, and separatists, are politically motivated. Many criminal organizations rely on fear or terror to achieve their goals and maintain control within their ranks. These groups may adopt tactics similar to those used by authoritarian regimes to maintain power. Some forms of organized crime exist simply to meet demand for illegal goods or to facilitate trade in products and services banned by the state, such as illegal drugs or firearms. In other cases, criminal organizations force people to do business with them, as when gangs extort protection money from shopkeepers. Street gangs may be classified as organized crime groups under broader definitions, or may develop sufficient discipline to be considered organized crime under stricter definitions.

A criminal organization can also be referred to as an outfit, a gangster/gang, thug, crime family, mafia, mobster/mob, (crime) ring, or syndicate; the network, subculture, and community of criminals involved in organized crime may be referred to as the underworld or gangland. Sociologists sometimes specifically distinguish a "mafia" as a type of organized crime group that specializes in the supply of extra-legal protection and quasi-law enforcement. Academic studies of the original "Mafia", the Sicilian Mafia, as well as its American counterpart, generated an economic study of organized crime groups and exerted great influence on studies of the Russian mafia, the Indonesian preman, the Chinese triads, the Hong Kong triads, the Indian thuggee, and the Japanese yakuza.

Kowloon Walled City (Chinese: 九龍城寨) was an extremely densely populated and largely lawless enclave of China within the boundaries of Kowloon City of former British Hong Kong. Built as an imperial Chinese military fort, the walled city became a de jure enclave after the New Territories were leased to the United Kingdom in 1898. Its population increased dramatically after the end of the Japanese occupation of Hong Kong during World War II, attracting mostly refugees fleeing the renewed Chinese Civil War.

By the late 1980s, the walled city contained roughly 35,000 residents within its territory of 2.6 hectares (6+1⁄2 acres), resulting in a staggering population density of over 1.2 million inhabitants per square kilometre (3 million inhabitants per square mile). As a result of the absence of any widely recognized bureaucracy, the city's residents and businesses had no municipal codes to govern them. Enabled by the enclave's anarchic nature, trade in banned products thrived, ranging from narcotics to dog meat. From the 1950s to the 1970s, it was controlled by local triad gangs and had high rates of prostitution, gambling, and drug abuse.