*(Following notes from wikipedia)* As in much of San Francisco, a period of criminality existed during the late 19th century; many tongs arose, trafficking in smuggling, gambling and prostitution. From the mid-1870s, turf battles sprang up over competing criminal enterprises. By the early 1880s, the term Tong war was being popularly used to describe these periods of violence in Chinatown. At their height in the 1880s and 1890s, twenty to thirty tongs ran highly profitable gambling houses, brothels, opium dens, and slave trade enterprises right there in Chinatown. Overcrowding, segregation and the lack of governmental control contributed to conditions that sustained the criminal tongs until the early 1920s.