The Tong Wars were a series of violent disputes beginning in the late 1800s among rival Chinese Tong factions centered in the Chinatowns of various American cities, in particular San Francisco. Tong wars could be triggered by a variety of inter-gang grievances, from the public besmirching of another Tong's honor, to failure to make full payment for a "slave girl", to the murder of a rival Tong member. Each Tong had salaried soldiers, known as boo how doy, who fought in Chinatown alleys and streets over the control of opium, prostitution, gambling and territory.