Chinatowns in the United States.
A lot were historically present in the mid 1800's. Supposedly they were to provide enclaves for the Chinese working on the railroads, mines and farms, etc.
1875 The Page Act was introduced to ban Chinese Women from immigrating.
1882 The Chinese Exclusion Act banned the immigration of all Chinese because they were supposedly taking all the jobs.
This was rescinded in 1943.
If you pay attention you also know that many 'Chinatowns' have underground components that still exist today. These tunnels were either already there when they moved in or they dug them out. Many towns in America boast of underground tunnels with storefronts and everything. This could be attributed to the Chinese hiding out or buried mudflood cities that were repurposed.
Most of the Chinese immigrants of the early expansion came from the HongKong area.