You might be interested in the history of Kowloon Walled City after WW2

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.