Two Chinese men in a San Francisco opium den.

San Francisco's Chinatown was the port of entry for early Hoisanese and Zhongshanese Chinese immigrants from the Guangdong province of southern China from the 1850s to the 1900s. The area was the one geographical region deeded by the city government and private property owners which allowed Chinese persons to inherit and inhabit dwellings within the city. The majority of these Chinese shopkeepers, restaurant owners, and hired workers in San Francisco Chinatown were predominantly Hoisanese and male. Many Chinese found jobs working for large companies seeking a source of labor, most famously as part of the Central Pacific on the Transcontinental Railroad. Other early immigrants worked as mine workers or independent prospectors hoping to strike it rich during the 1849 Gold Rush. (Photo by: Pictures From History/Universal Images Group via Getty Images)