Human zoos (also called "ethnological expositions" or "Negro Villages") were 19th and 20th century public exhibits of humans, usually in a "natural" or "primitive" state. The displays often emphasized the cultural differences between Europeans of Western civilisation and non-European peoples. Ethnographic zoos were often predicated on unilinealism, scientific racism, and a version of Social Darwinism. A number of them placed indigenous people (particularly Africans) in a continuum somewhere between the great apes and humans of European descent. (Source: Wikipedia)
Such zoos could be found in New York, London, Warsaw, Barcelona, Hamburg and other cities around the world with up to 300,000 visitors attending each display.
A Negro Village was the main attraction at the 1889 Parisian World’s Fair. About 28 million people visited it.
Human zoos were so popular in Germany that even German-Prussian statesman of the late 19th century Bismarck attended one of them.
These five Indians from Kawesqar tribe were kidnapped from Chile in 1881 to be exhibited in one of the European human zoos. They all died within a year.
Africans were often exhibited next to monkeys to show that they were closer to animals than to humans.
PS: These are Japanese prostitutes in the end of the 19th century.