It's not often that a film has an impact past the box office, but one documentary has helped tell the truth about the Texas Gulf Coast's long-disparaged Karankawa people.

For years, the Indigenous Peoples of the Coastal Bend and the Karankawa Tribe of Texas have fought for a corrected Texas Historical Commission marker in Corpus Christi. Houstonian Adán Medrano’s 2021 film, Truly Texas Mexican, helped finalize a push that will lead to a long-due correction on July 25.

The old marker was plainly offensive. Not only did it say the Karankawa people had "gained a reputation for savagery," but it repeated the long-discredited claim that they practiced cannibalism — a contention born out of the colonial need to justify violence against the tribe.

Medrano, a San Antonio native who currently lives in Houston, became part of the fight when he stood in front of the marker and made a direct appeal to correct the sign.

"I call upon the historians who live in Texas to come up and stand up and say, 'Take this down. This is a lie,'" he said during a scene in Truly Texas Mexican.

Two of them heard the call. Texas A&M University–Corpus Christi history professor Dr. Peter Moore and historian Dr. Tim Seiter of the University of Texas at Tyler joined the years-long Indigenous effort following the film's release. Led by the Indigenous Peoples of the Coastal Bend and the Karankawa Tribe of Texas, the academics helped research and draft a replacement that honors them as one of Texas' first peoples.

The marker not only replaces racist mythmaking with scholarship and tribal knowledge, it presents the fact that Karankawa descendants aren't a historical footnote but a living community still present in South Texas today.

Medrano's advocacy here continues his work with the Texas Indigenous Food Project, a nonprofit dedicated to celebrating the Indigenous foodways of Texas and the Americas. But in many ways it is a continuation of a career devoted to amplifying voices rarely heard in popular culture. In 1976, he founded San Antonio's CineFestival, now the nation's longest-running Latine film festival.

At 10 am on July 25, representatives of the Indigenous Peoples of the Coastal Bend and the Karankawa Tribe of Texas will unveil the corrected marker, joined by Medrano. Visitors can find it at 6001 Ennis Joslin Rd.