New York ? The bone-jarring, head-banging sport of bronco busting seemed almost easy to Jackson Sundown, after his audacious escapes on horseback from U.S. troops in the Nez Perce Wars.

Sundown was in his 50s when he reached rodeo’s pinnacle in 1916, becoming the first American Indian to win the world bucking championship and hold the all-around title at the Pendleton Roundup.

“Sundown! Sundown! Ride ’em Sundown!” crowds yelled as the wiry cowboy kept his seat and tamed the jackknife kicks of the big bay, Angel. His ride at the rodeo mecca in eastern Oregon made him one of the early American Indian heroes of the spectacle.

Tom Three Persons, of the Kainai in Alberta, Canada, is another storied figure in rodeo lore. He won the world saddle bronc title at the first Calgary Stampede in 1912.

Their exploits are described in “Legends of Our Times: Native Ranching and Rodeo Life on the Plains and Plateau,” a compelling new exhibit at the Smithsonian’s National Museum of the American Indian in Lower Manhattan.

Converging worlds

The displays puncture an Old West myth about separate, mutually hostile worlds of cowboys and Indians. In reality, they converged.

The splendid collection of 700 relics from the 19th and 20th centuries encompasses antique saddles and bridles, buckskin attire and saddle bags, powwow regalia resplendent with beadwork, tribal headdresses, buffalo-skin overcoats, leather chaps, rifle cases and hunting knife scabbards.

Photos documenting native ranching and rodeo exploits were gathered by the Canadian Museum of Civilization in Ottawa from hundreds of tribal and other sources on both sides of the border in a six-year effort. The traveling exhibit was earlier shown at the Cowboy Hall of Fame in Oklahoma City.

Wallboards in English and French explain how Indian cowboys evolved from buffalo hunters to reservation ranchers and then became respected rivals of white cowboys on North American rodeos.

“People tend to look at stereotypes, saying they didn’t realize that Indians could be cowboys,” said Gerald McMaster, deputy assistant director for cultural resources at the museum. “Native people have been contributing for hundreds of years.”

Ranching “was a natural crossover — a way of life based on a horse culture, their experience of driving herds of deer and buffalo, their knowledge of the land for grazing,” said McMaster, 50, a Plains Cree from Ontario, Canada.

The exhibit, which opened Saturday and runs through March 7, occupies a 200-foot-long gallery in the ornate former Customs House at Battery Park. Admission is free.

Indian cowboys

The survey begins with descriptions of the sacred role of horses, dogs and buffalo in Plains and Plateau tribal societies, and how these beliefs influenced native cowboys’ views of ranching and rodeo life.

Other installations describe the evolution of Indian ranching, rodeo events, native entertainers in Western films, music and pageants, and native artisans — saddlemakers, clothing designers and silversmiths.

Equestrian skills were a matter of life-or-death for the Plains people, essential for hunting buffalo and other game and fending off marauding rivals. The arrival of white settlers led to bitter conflicts about land and the slaughter of buffalo herds, ending unfettered migration of tribes.

Confined to reservations, Indians found that horsemanship and other life-sustaining skills were ideal for their cattle ranching. They became adept at roping calves, branding steers and growing hay for winter feed.

Many Indian cowboys hired out to the huge cattle drives to railheads that brought beef to eastern markets in the 19th century. When rodeo competitions blossomed in the early 20th century, Indian ranch hands were able to challenge white cowboys in events like roping bronco busting, old skills passed down from tribal taming of wild horses.

Sundown’s story is emblematic of Native American resilience and adaptability.

As a teenager in 1877, Sundown joined Chief Joseph’s band in their epic flight from the Nez Perce reservation in Idaho, pursued by U.S. troops. At the Battle of Big Hole in Montana, Sundown managed to escape after hiding under buffalo robes in a teepee when the bluecoats set the camp afire and killed many women and children.

After the Battle of Bear Paw Mountain, he escaped to Canada where he found refuge with Chief Sitting Bull, himself a fugitive after the Battle of the Little Bighorn a year earlier.

He returned to a reservation in Montana in the 1880s and mastered rodeo skills. Sundown didn’t start competing until he turned 40.