A new film aims to highlight a Nazi "secret" mission to sterilize hundreds of Afro German children.

(CNN) In 1937, mixed race children living in the Rhineland were tracked down by the Gestapo and sterilized on " secret order ." Some were later the subject of medical experiments, while others vanished .

"There were known to be around 800 Rhineland children at the time," says historian Eve Rosenhaft, professor of German Historical Studies, at the University of Liverpool.

It was a little known part of Holocaust history until Mo Abudu, chief executive of Nigerian media network EbonyLife TV, read an online article by Rosenhaft on the plight of these children.

"When I read about it [the article] I just thought we need to put this to screen," says Abudu. "There are many children in that era born of African and German parentage and I felt what happened to those people. Their stories are totally untold."

Essentially these children were pulled from school, off the streets and bundled into vans, taken to medical facilities and sterilized." Nicole Brown, researcher

It is the studio's first foray into the international film market and a dramatic change in subject matter for Nollywood, which is famous for producing movies that focus on lighthearted story lines.

"I don't see this as a Nollywood film at all," says Abudu. "I believe this is a film that has global appeal."

In developing the film's plot, she commissioned scriptwriter Nicole Brown to further investigate.

Caption: Two survivors prepare food outside the barracks. The man on the right is thought to be Jean (Johnny) Voste, born in Belgian Congo -- the only black prisoner in Dachau. Photo Credit: United States Holocaust Memorial Museum, courtesy of Frank Manucci. Date: May 1945

A story buried

"Essentially these children were pulled from school, off the streets and bundled into vans, taken to medical facilities and sterilized," says Brown.

"Although their births were recorded, what happened to almost the majority of them is unknown," she adds. "In a way we wanted to tell a story that had been buried for so long."

Thousands of black people were living in Germany when Hitler came to power. Some were from former colonial countries. Others, mainly in the Rhineland, were the offspring of World War I colonial troops and German mothers.

We walked around in exotic dress and played Africa." Theodor Michael

Taking the extremely scarce autobiographies of Afro German survivors as its inspiration, the film's script follows the relationship of a fictionalized mixed race couple living in Nazi Germany, and their fight to save their child.

Ava is the daughter of a wealthy German industrialist and Nazi sympathizer. Duante is a Cameroonian who works in her father's factory. The pair fall in love and must get their little girl out of the country or risk sterilization and the concentration camp.

It took Brown months of painstaking research to flesh out this extraordinary chain of events. One of the stories she came across in her research was that of Theodor Wonja Michael.

'A German in a grass skirt'

Today, Michael lives in Cologne surrounded by his grandchildren. This would not have been the case had the Nazis won.

"Our family did not differ from [any] habits of other families in Germany," the 92-year-old told CNN. "I was then not aware of the complication of mixed [race] families because this was normality in my early life."

It wasn't until Adolf Hitler rose to power that Michael and his family would be stripped of their German passports and rendered stateless.

Under the 1935 Nuremberg laws mixed marriages were banned

Although not sterilized, Michael ended up in a forced labor camp when he was 18.

Born in 1925, he was the youngest son of an African and a white German mother. His father, Theophilus Wonja Michael had arrived in 1894 from Cameroon (then part of the German empire) to study and work.

Upon arrival, Michael's father would quickly realize the only occupation available was playing the "exotic African" in human exhibition shows. The whole family would later take part, including Michael and his three siblings.

Human exhibitions

"Völkerschau" translated as "human shows," stems from the 15th century. According to research by German historian Anne Dreesbach , world explorers such as Christopher Columbus brought "exotic" native people home for display.

Wild animal merchant Carl Hagenbeck popularized "Völkerschau" in Germany in 1874. He struck upon the idea of an exhibition where you could see animals and humans from lands afar in their "natural" state.

By the 1930s, Dreesbach says there were some 400 human exhibitions in Germany.

At the camp he would live in constant fear of having to see a doctor and consequently being sterilized.

An offshoot of this was the Deutsche Afrika-Schau, which Michael became part of. Here, increased emphasis was placed on representing the customs of lost colonies.

As second and third generation Afro Germans began to take part in the exhibitions, many of the dances and mannerisms they displayed to the amusements of crowds were stereotypes, believes Robbie Aitken, a historian at Sheffield Hallam University.

"What they are performing on stage, like many who are in ethnographic exhibitions, are essentially inauthentic, but it's a way of earning a living," says Aitken.

Michael described the experience as being "a German in a grass skirt."

"We walked around in exotic dress and played Africa," he told German documentary series 'Schwarz Rot Gold.'

Banned from public school

In 1941, black children were officially excluded from public schools as part of the law that had banned Jewish children. They weren't permitted to go on to high school, university or professional training.

By the 1940s, the Africa shows shut down. Unable to get a formal education, Michael began to work as an extra in propaganda films, which glorified Germany's past empire and racial superiority.

Despite being German-born, Michael was marched with other Afro Germans into a forced labor camp near Berlin to work as a "foreign" laborer in 1943.

"I think they didn't know what to do with me. They could have done worse, put me in a concentration camp, but they had no legal grounds to arrest me."

At the camp he lived in constant fear of having to see a doctor and consequently being sterilized

Under the laws of Nuremberg, this was an offense against the Aryan race ... after the war it was love when we married." Theodor Michael

Theoretically he could have tried to escape, says Michael. Others had attempted to do so. But where would he go?

"Because of my African appearance it was impossible to make a single step in the then white world, without being noticed every time by everyone," he says.

Soviet Troops liberated the camp in 1945. After the war he married a white refugee. The marriage lasted 47 years before the death of his wife in 1994.

"Under the laws of Nuremberg, this was an offense against the Aryan race and due to persecution. It was of course not so after the war ... it was love when we married," he recalls.

Having survived the Nazi era, it would be decades before Michael was finally able to tell his own story in an autobiography, breaking a long held silence.

"My children and even more my grandchildren urged me to write," says Michael.

"All this couldn't happen until I had gained some distance from my former life...

"I never thought that this book would become international interest," he says.

"We definitely wanted to highlight the horror inflicted on these children," says the film's scriptwriter. They looked at the life of Afro German Gert Schramm, who shares a story similar story to Michael's.

They were there till 11 a.m. just standing there outside in the snow and it was so very cold and they'd had no food or water."

The black prisoner of Buchenwald

Born in 1928 in the sweeping medieval city of Erfurt in East Germany, Schramm was the child of an African-American father and German mother at a time when racial tensions had begun to simmer.

At 15, he became a "political prisoner" in Buchenwald concentration camp and was threatened with sterilization.

Gert Schramm who survived Buchenwald concentration camp.

On the reason for his internment, "all the evidence suggests it really was because he was mixed blood," says Rosenhaft.

His friend, Dr. Pierrette Herzberger-Fofana, recalls Schramm telling her, "at 5 a.m. in the morning they would be told to line up. ...

"He remembered one morning they were there 'til 11 a.m. just standing there outside in the snow and it was so very cold and they'd had no food or water. Daily they were given something resembling soup but it was not soup."

They were liberated by US soldiers in 1945. Herzberger-fofana believes he never fully recovered from his country's rejection of him just because of his skin color. "He was an unhappy man," she says.

Schramm passed away on April 18 last year. "These are stories out there but it's not in anyone's consciousness," says Abudu.

'Records were destroyed'

On the script, Brown was keen to ensure these monumental life experiences would not be condensed to "torture," but that the story would be about hope.

"We could have had much of the film in a concentration camp where they do suffer terribly there or they do end up in a gas chamber. ...

"But we felt that wasn't the story here. Instead we focused more on their plight in terms of their color in that environment," explains Brown.

"These are stories out there but it's not in anyone's consciousness." Mo Abudu, chief executive, EbonyLife TV

"It was important what angle we had in the story," she says. "Getting the script right took months," adds Abudu. There were 15 weeks of revisions. Brown believes one of the reasons these stories were sidelined for so long was the numbers affected.

"You are talking about millions of Jewish people dying at the hands of Hitler ... in the greater scheme of the Holocaust and how many children perished, it sounds horrible to say the words, but 800 mixed race children doesn't sound a lot, but that's still 800 children, regardless, that many people around the world didn't know existed," she says.

Another "problem is that the Nazis destroyed a lot of their records. There's not many black people left in Germany post 1945 who could then have been asked about what happened to them. There is no visible community as such by that point," adds Aitken.

EbonyLife is drawing up a casting list to begin filming later this year. For the few survivors who remain, it's a memory that still haunts.

Race "still plays too great a role in human relations," Michael says. "It is generally not noticed that human beings have only one root [have the same origin]."