The criminal abuse that King Leopold II of Belgium notoriously visited upon the people of the Congo River Basin, beginning with his illicit appropriation in the 1880s of the vast territory he called the Congo Free State, did not end after he ceded control of the colony to the Belgian Parliament in 1908. For many more decades, brutal apartheid existed in the Belgian Congo and adjacent colonies—Belgium also gained the territory known as Ruanda-Urundi, corresponding to the present-day republics of Rwanda and Burundi—and this forced segregation gave rise to an especially heinous policy that is only now coming fully into view.

Marriage between white and Black people was made impossible by colonial administrators. Children of mixed-race parentage were not officially recognized by the state, which depended upon clear hierarchies and distinctions of race. While those who had been acknowledged by their European fathers or mothers were allowed to live with their families, the disavowed children were registered as members of the “civilized native population,” placing them under the guardianship of the state. The children were taken young, in some cases as soon as they could go to the bathroom on their own. African parents who refused to release their toddlers were threatened with reprisals, including jail time. Many of the abducted children would never see either parent again. Estimates vary, but the number of young people affected by this colonial policy, which officially ended in the 1960s, is certainly in the many thousands.

Monique Bitu Bingi remembers all too clearly the final time the tall white man showed up in her village. The year was 1953, and she was living with her mother, grandparents, aunts and uncles in a scattering of mud-and-thatch huts in the Kasai region of what was then the Belgian Congo. They had all seen the man before; he showed up periodically to check on the cotton plantings that each household was required to cultivate. On this occasion, he spoke with one of her uncles, and later on, back at her grandparents’ hut, the 4-year-old noticed that a grim mood had descended over the grown-ups. She lay down to sleep beside her grandmother, her mother having disappeared from the compound.

The next thing Bitu Bingi remembers is waking by a large river. Her uncle helped her into a long, narrow canoe. After she and her grandmother, aunt and uncle disembarked on the opposite shore, the four of them walked for three days, the adults taking turns carrying little Monique. At night, they bedded down in huts that villagers had built for storing cotton. Eventually they came to a hospital, where the tall Belgian stood waiting by his truck. Some men lifted a cot holding a lifeless child into the back of it, and her aunt and uncle climbed up, too, settling in amid the bales of cotton. Bitu Bingi and her grandmother were instructed to sit up front.

She recalls waking a second time in the middle of a festival, surrounded by a crowd of people dancing. It must have been a Wednesday; that was the traditional day for a wedding. She searched the faces of the revelers but didn’t recognize a soul. Eventually, a girl a few years older than she approached, holding a mango in her outstretched hand. Taking young Monique by the arm, she led her to a place where women in long, white dresses, with billowing white fabric framing their pale faces, wandered among large buildings. A clutch of girls with brown skin similar to Bitu Bingi’s own began to gather around her. “It was another world,” she said. “I was somewhere else, and I didn’t know anyone.”

It is only recently that Bitu Bingi and others of mixed race—who were known as “mulâtres,” from the Latin word mulus (the offspring of a horse and a donkey)—have begun to speak publicly about how they were abducted from their homes as toddlers and installed in religious schools by the Belgian state. I first learned about these injustices in the course of my reporting on the palm oil industry for a recent book. The commodity was central to the economy of the Congo under colonial rule, and the same racist mind-set underpinned the cultivation of the oil palm crop, which relied on forced labor.