“War Pony,” set on the Pine Ridge Reservation, began as a project among friends and developed into a communal effort over seven years, according to directors Gina Gammell and Riley Keough, who made their directorial debut at the Cannes Film Festival.

The film is set on the sovereign grounds of the Oglala Lakota in South Dakota and follows the ups and downs of 12-year-old Matho, portrayed by LaDainian Crazy Thunder, and Bill, played by Jojo Bapteise Whiting.

“It started with us doing a film with our buddies,” Keough told Reuters of the idea, which dates back to 2015, when Keough met Bill Reddy and Franklin Sioux Bob as extras on the set of “American Honey.”

She became friends with the couple and, together with Gammell, proposed they make a film about their life.

“How to interact ethically amongst communities… sort of became our purpose,” Keough explained, detailing a process that involved writing workshops, improvisation sessions, and meeting hundreds of individuals in order to assemble a local cast.

“These are not film subjects; they are our very close, loving friends and family at this time.”

Meanwhile, Sioux Bob thinks the film will be a catalyst for change.

“This is a Native narrative delivered by authentic Native speakers.” “I’m hoping this may be a project that opens doors,” he remarked.

The film’s screening in the “Un Certain Regard” category at Cannes has added meaning for Keough, who is also attending the festival to see Baz Luhrmann’s film about her grandpa, Elvis Presley.

“I believe that everything occurs for a reason,” Keough explained, adding that Luhrmann did “an great job conveying our tale, our family story.”