At the beginning of the 20th century, Edward S. Curtis set out to document what he saw as a disappearing race: the Native American. From 1907 to 1930, Curtis took more than 2,000 photos of 80 tribes stretching from the Great Plains to the Pacific Northwest and Alaska. He then published and sold these photos, along with narrative text, in 20 volumes of work known as “The North American Indian”. It is one of the most significant collections of its kind, “probably the most important photographic document of its age and its topic,” said Jeffrey Garrett, associate university librarian for Special Libraries at Northwestern University. (Photo by Edward S. Curtis)

A physically challenged girl looks at her brother as she is kept in a basin to seek alms from people on the street in Kano, Nigeria December 30, 2015. The girl has suffered from her condition since birth. (Photo by Reuters/Stringer)

In this photo taken on Thursday, July 23, 2015 migrants enter a train to Serbia at the railway station in the southern Macedonian town of Gevgelija. The country has become a major transit route for thousands of Middle Eastern and African refugees and migrants who cross over from Greece and then continue into Serbia. (Photo by Boris Grdanoski/AP Photo)

An injured girl reacts at a site hit by an airstrike in the rebel-held Douma neighbourhood of Damascus, Syria November 7, 2016. (Photo by Bassam Khabieh/Reuters)

An internally displaced Afghan girl holds a child at a refugee camp in Kabul, Afghanistan May 31, 2016. (Photo by Mohammad Ismail/Reuters)

Young girls attend a training session in MGFSO Olympic reserve school in Moscow on May 30, 2016. (Photo by Kirill Kudryavtsev/AFP Photo)

A girl and boy carry a basket of fish in Kyaukpyu township, Rakhine state, Myanmar October 6, 2015. (Photo by Soe Zeya Tun/Reuters)