NEW YORK—George Catlin's lurid painting of Mandan Indians undergoing an excruciating ritual caused a sensation among 19th-century audiences eager for news about the Wild West.

The youths in loincloths are depicted hanging by cords attached to wooden splints that pierce their shoulders and chests, their heads lolling in agony. Other young braves sit dazed and bloodied, having survived being hoisted atop the medicine lodge as tribal elders watch the coming-of-age ordeal.

"Thank God, it is over, that I have seen it and am able to tell it to the world," Catlin wrote in his 1832 journal before painting the "horrid and frightful" scene from his own sketch of the O-kee-pa ritual at a Mandan village on the Upper Missouri River. When he took his "Gallery of American Indians" on tours of the East Coast and European capitals, critics accused him of inventing the "Cutting Scene." Doubts persisted until Indian agents confirmed what Catlin had witnessed and recorded in a four-picture series.

More than 100 of Catlin's renowned paintings from his decade of travels to tribal areas on the Great Plains, including the cutting scene loaned by the Denver Art Museum, are on display until Sept. 5 at the National Museum of the American Indian, George Gustav Heye Center.

It's the final stop for the Catlin exhibition, launched at the Renwick Gallery of the Smithsonian American Art Museum in Washington, D.C., in 2002. The show then traveled to museums in Kansas City, Mo., Los Angeles, Houston and finally to New York City to mark the bicentennial of Lewis and Clark's transcontinental trek.

Catlin's works form a unique historical record of American Indians on the Great Plains in the final years of tribal sovereignty before the mass influx of white settlers forced them onto reservations. The paintings are considered a "crown jewel" of the Smithsonian collection.

Catlin's wilderness trips in the 1830s brought him face to face with 50 tribes in widely scattered regions. He produced hundreds of oil paintings in a dramatic, earthy style, from formal portraits of warriors, medicine men, women and children, to renderings of lacrosse games, scalp dances and buffalo hunts on the vast prairies.

Highly sympathetic to the tribes, Catlin avoided painting many harsh realities of the nomadic societies. But his travel letters are candid about customs that engrossed his audiences: polygamy and child brides; women forced to do much of the work; old people abandoned on the trail; continuous warfare over hunting areas; and corruption and disease brought by whites.

Catlin focused his paintings on "leaders and others of extraordinary talent or accomplishment, the 'dignitaries' who represented the best in a community," according to a catalog of the show.

His portraits capture the strength and pride of chiefs such as Black Hawk and Keokuk of the Sac and Fox, Osceola of the Seminoles, Buffalo Bull's Back Fat of the Blackfoot and warriors like Rabbit's Skin Leggings of the Nez Perce and Buffalo Bull of the Pawnees.

A full-length likeness of Four Bears, second chief of the Mandan/Numakiki, is described by the curators as one of the most influential American portraits ever painted.

"No tragedian ever trod the stage, nor gladiator ever entered the Roman Forum, with more grace and manly dignity, than did Four Bears as he arrived for his sitting," Catlin wrote in his flowery prose.

Catlin had to paint fast in the wilderness. He focused on the subject's face and totem, such as an animal sign painted on a deerskin garment, then completed the torso, costume details and background on return to his studios. Most of his pictures are 29 inches by 24 inches, a standard size for easy stacking and transport.

A lawyer and struggling portrait painter, Catlin decided to go West to paint the tribes on their own lands after seeing Indians traveling through Philadelphia on their way to Washington in the late 1820s. He made his first journey to the West in 1830, carrying rolls of canvas, an easel and fish bladders filled with oil colors, leaving his family behind in the East.

In 1837, Catlin began touring the East Coast and Europe with his collection of paintings, tribal costumes, weapons and household artifacts. He went into debt to finance exhibitions and publish his writings but enjoyed considerable success gaining an audience with Queen Victoria in London and a commission to paint Western scenes in Paris.