Native American civil rights leader Clyde Bellecourt has died. He was 85.

According to the Minneapolis Star-Tribune, his wife Peggy confirmed that Bellecourt passed away on Tuesday after battling prostate cancer.

One of the most prominent Native American activists and organizers to have ever lived, Bellecourt was born on the White Earth Indian Reservation in 1936. In 1968, he co-founded the the American Indian Movement (AIM) in Minneapolis to advocate for tribal sovereignty, as well as better housing, job opportunities, health care, education and legal services for Native American communities.

"He fought for the visibility and fair treatment of Native people," Minnesota Lt. Gov. Peggy Flanagan, a member of the White Earth Band of Ojibwe, told the Star-Tribune. "Minneapolis has one of the most robust and vibrant networks of organizations serving the urban Indian community in the country, and that is because of Clyde and his work."

Since its inception, AIM has become a global organization advocating for the civil rights of over 375 million Indigenous people around the world, per NPR. In the very beginning though, it was a grassroots movement that tried to combat police brutality and discrimination against Native Americans. In order to do that, AIM organized neighborhood patrols, created protocols to hold the police accountable and prevent members of their communities from having their rights violated, with Bellecourt ultimately becoming the co-chair of the Minneapolis Police Community Relations Council.

Additionally, Bellecourt fought against the usage of racist sports mascots and names. He also helped create the National Coalition on Racism in Sports and the Media and organized marches during the 1991 World Series final between the Minnesota Twins and the Atlanta Braves, as well as the 1992 Super Bowl game between the Washington Redskins and the Buffalo Bills.

“At the end of the day, it’s about his grandkids, you know, and ensuring that their kids and their grandkids will have equity,” AIM executive director Lisa Bellanger told CBS Minnesota affiliate WCCO, before reciting a message that Bellecourt himself wanted her to carry on.

“’Stay at the table. You gotta keep working. You can’t give up,’” she relayed.

“We can’t just be a silent voice," Bellanger went on to add for herself. "We have to be out there."

Read the Star-Tribune's entire obituary here.

Photo via Getty / Dave Buresh / The Denver Post