The serene municipality of Songea is steeped in a history of violence. This remote corner of southern Tanzania was a centre of resistance to colonial rule during the early 20th century, when German colonialists executed local people and took the remains of many back to Europe.

For decades, descendants of some of those who took part in the revolt have fought a largely overlooked campaign for their ancestors’ atonement and for the repatriation of their remains. Now a documentary co-directed by the German film-maker Agnes Lisa Wegner and her Tanzanian counterpart Cece Mlay has shone a delicate light on two families’ search for answers.

“The question of ancestral remains was not something that I had thought had happened here,” said Mlay. “It almost changes your worldview about how you perceive your familial relationships.”

As people in Songea and other parts of German east Africa, which is made up of areas including present-day Burundi, Rwanda and mainland Tanzania, waged resistance against German rule, the colonial forces publicly hanged revolters.

They later stole the skulls and bones of some people and took them to Germany for experiments in the racist science of phrenology, which was used to support claims of European racial superiority.

The movement to repatriate the remains has begun to gain momentum. In the documentary, two families fight bureaucracy as they try to get information and bring back the body parts of their ancestors.

Wegner said she had conceived the film in 2015, after an encounter with the South African history professor, Ciraj Rassool, who with his colleague Martin Legassick discovered how the remains of the Khoisan couple Klaas and Trooi Pienaar were stolen in 1909 and taken to Vienna for scientific experiments before being kept in a museum. The remains were repatriated and buried in 2012. The story shook Wegner to her core.

Wegner knew immediately that she would have to make the documentary in close collaboration with Tanzanian film-makers, so in 2021 she reached out to Kijiweni Productions, an independent production house where Mlay works. “We were very much aware of the issue of perspective,” she said.

The Empty Grave follows two families in their complex quest to find and return the remains of their ancestors.

In Songea, John Mbano, a legal officer, and his wife Cesilia, a primary school history teacher, are looking for the remains of Mbano’s great-great-grandfather, Nduna (sub-chief) Songea Mbano.

A leader of the Ngoni people, Songea was hanged by German colonialists in 1906 during the Maji Maji war. After his burial his head was stolen and taken to Germany.

John and Cesilia’s search takes them to Berlin, where they meet state minister Katja Keul and ask for the remains to be found and returned. They visit the archaeological centre of the Prussian Cultural Heritage Foundation, which holds thousands of stolen human remains.

“Spiritually, the head of the person is everything,” John Mbano tells Keul in the film. “So, when his head was cut [off] and sent somewhere else, that means the whole community lost its ideas, rituals.”

Mangi (Chief) Lobulu Kaaya of the Meru community of northern Tanzania was hanged by German colonialists in 1900 and his skeleton was taken to Berlin. Kaaya’s remains were found in 2022 in the US, where they had been sent from Berlin.

In the documentary, descendants Felix and Ernest Kaaya try to navigate the bureaucracy of repatriation and come to terms with their ancestor’s history. In one scene, Ernest breaks down when he visits for the first time the tree on which Lobulu was hanged. “He suffered. He really suffered, if they did that to him,” he says, touching the tree.

Mlay said this scene marked a moment when “the reality of the work that you’re doing meets the camera”, and was the most challenging to shoot, as it showed the impact of intergenerational trauma on the descendants.

Tanganyika – as mainland Tanzania was known – was under brutal German rule from 1885 to 1918. During that period, the Germans faced dozens of resistance movements against their occupation, the deadliest being the Maji Maji war from 1905 to 1907, in which 300,000 people are believed to have died.

The legacy of German colonialism in Tanganyika hangs like a dark cloud over both countries. The Tanzanian and German governments have been hesitant to investigate and confront it, but as African people have learned more about colonialism and pushed for the return of stolen heritages, the narrative has been changing.

Last year Germany’s president Frank-Walter Steinmeier travelled to Songea, where he met descendants of Songea Mbano, publicly apologised for colonial-era crimes, and said his country would seek to find and repatriate the remains of Songea Mbano and others.

The documentary premiered at the Berlin International Film Festival in February before being shown at German cinemas. It has also had public screenings in Dar es Salaam, Songea and Meru, and there are plans for more.

“Our priority has been to make sure the film plays in the spaces where the families are from,” said Amil Shivji, a co-producer and the founder of Kijiweni Productions. “Not only to pay respect to the families alive and dead, but also to give confidence to more people to come forward and speak about potentially missing ancestors.”

Wegner said that as a German and in the context of atrocities committed by Germans, she felt a sense of responsibility throughout the making of the film. “[The story] had been shoved under the carpet for way too long,” she said.

For Shivji, who like Mlay was not familiar with the story before the making of the film – learning about the sheer number of skulls and bones that are stored abroad was shocking. “Colonialism had no parameters of justice,” he said. “It’s hard to go to bed at night knowing this information.”