A complete set of Edward S. Curtis' The North American Indian, a collection of photographs from the early 1900s that recorded First Nations people and customs, has sold for $1.2 million US.

Swann Auction Galleries in New York sold the 20-volume set on Thursday during an auction of fine photographs and photobooks.

Curtis began photographing North American natives in 1906 in order to document their way of life and collected 40,000 images over the next 24 years.

His staged portraits of proud people sporting their headdresses and wearing the fine embroidery or beadwork of their tribes have come to be considered valuable as a record of First Nations traditions.

Montreal’s McCord Museum hosted an exhibit of photos drawn from the collection earlier this year.

The collection sold Thursday includes 722 large-format photogravures, 1,500 additional images collected in a 20-volume set, four maps and two diagrams, all from Curtis’s original copper plates. Curtis also created text to accompany his photos, much of it revealing the beliefs of the day, including the perception of Indians as a "vanishing race."

The Wisconsin-born photographer gained access to more than 100 separate tribes and learned several native languages as he sought to gain the trust of First Nations people.

Curtis's project to document North American Indians was underwritten by industrialist J.P. Morgan and endorsed by President Theodore Roosevelt. There is a complete set of the photos in Washington's Smithsonian Institute.