In 1879, U.S. cavalry captain Richard Henry Pratt opened a boarding school in Carlisle, Pennsylvania. But it wasn’t the kind of boarding school that rich parents send their children to. Rather, the Carlisle Indian Industrial School was a government-backed institution that forcibly separated Native American children from their parents in order to, as Pratt put it, “kill the Indian in him, and save the man.”

Over the next several decades, Carlisle served as a model for nearly 150 such schools that opened around the country. Like the 1887 Dawes Act that reallotted Native American land, or the Bureau of Indian Affairs’ 1902 “haircut order” specifying that men with long hair couldn’t receive rations, Native American boarding schools were a method of forced assimilation. The end goal of these measures was to make Native people more like the white Anglo-Americans who had taken over their land.

At boarding schools, staff forced Indigenous students to cut their hair and use new, Anglo-American names. They forbid children from speaking their Native language and observing their religious and cultural practices. And by removing them from their homes, the schools disrupted students’ relationships with their families and other members of their tribe. Once they returned home, children struggled to relate to their families after being taught that it was wrong to speak their language or practice their religion.

“Through breaking bonds to culture, they [broke] bonds to one another,” says Doug Kiel, a history professor at Northwestern University. “It’s a way of destroying a community.”

Some students never made it home at all. Boarding schools were susceptible to deadly infections like tuberculosis and the flu, and schools like Carlisle had cemeteries for dead students. Between Carlisle’s founding 1879 and its closing 1918, the school buried nearly 200 children in its cemetery. In 2017, the Northern Arapaho tribe successfully petitioned the U.S. government to return the remains of two boys who died at Carlisle.

Students who did survive were marked by trauma. Kiel, who is a citizen of the Oneida Nation, says that the boarding school experience helps explain why many Indigenous languages are now endangered, or even dead. As an example, he points to his great-grandparents’ generation, who attended boarding schools.

“My grandmother recalled hearing the Oneida language being spoken around her by the people who were the adults, but they chose not to teach it to children,” he says. “Why? Because it was a source of trauma for them. And they had been told that it was backwards, that it was uncivilized, that it was of the past, that there was no utility in speaking it.” Some thought that speaking it would only be a burden to their children.

Boarding schools based on the Carlisle model fizzled out in the early 20th century. But after that, the rupture of Native American families continued in other ways. By the 1940s, “Native kids are simply being deemed to be in unfit households with unfit mothers,” Kiel says.

“That’s not official government policy,” he continues. “But it’s a racially-biased perception of Native families, of Native homes, of Native mothers that has the effect of forcibly removing Native children from their homes and placing them into, generally, the homes of white people in ways that serve to cut Native people off from their communities.”

Congress passed the 1978 Indian Child Welfare Act based on research that “25–35 percent of all Native children were being removed; of these, 85 percent were placed outside of their families and communities—even when fit and willing relatives were available,” according to the National Indian Child Welfare Association’s website. With the act, tribes won the ability to determine the residency of children in that tribe.

The Department of Health and Human Services acknowledged in 2016 that Black and Native children were overrepresented in the child welfare services. And though new laws like the 1990 Native American Languages Act have protected Indigenous children’s right to learn their own language and history in Bureau of Indian Education schools, significant educational inequalities remain between Indigenous and non-Native students.