OWASSO, Oklahoma - 12 Million people were taken from Africa and sold into slavery in the nearly 400 years of the slave trade. The Smithsonian Institution tells a portion of that story using photographs taken by an Owasso photographer.

Photographer Doug Henderson said it means a lot to have a dozen or so of his photographs on display at the National Museum of African American History and Culture in Washington DC.

“They are good pictures.” He says, “But they are there because of their content.”

He was working in Africa back in 2004 photographing AIDS research work being done there. He ran across one of the huge fortress type structures, called slave castles, used to house captives while waiting for a slave ship to arrive.

He knew there were more and wanted to go back, so in 2010 he and fellow photographer Greg Merrell put a trip together and photographed 30 of these Slave Castles and the people who live around them now.

When the Smithsonian was putting together the African American History Museum they contacted Doug.

"I got a call from them and they said you're the only one who has any of these,” he said.

Earlier this month he spent a couple of days touring the museum watching people see his photographs for the first time and realize these structures are a part of their own story.

It was emotional, he said. “They're standing there with tears running down their cheeks ... it's a bewildering experience that I've shot pictures that have touched them in that way."