Here should be a well known movie staring two really good actors, Leonardo DiCaprio (Titanic, The Departed) and Russell Crowe (American Gangster, Gladiator). This is the first releases (of many) of this movie.

Gangs and criminal organizations come into creation for a number of reasons or motives. Usually they revolve around money, and use fear, crime and extortion. They can be loosely controlled with no apparent structure, or they can be highly efficient with military like organization.