Mr. Wilson is one of 5,000 young men from the Oglala Sioux tribe involved with at least 39 gangs on the Pine Ridge Indian Reservation. The gangs are being blamed for an increase in vandalism, theft, violence and fear that is altering the texture of life here and in other parts of American Indian territory.

Image THE PALLBEARER Richard Wilson, left, has carried the coffins of five gang members from Pine Ridge, S.D. At right, his half-brother, Richard Lame. Credit... Matthew Williams for The New York Times

This stunning land of crumpled prairie, horse pastures turned tawny in the autumn and sunflower farms is marred by an astonishing number of roadside crosses and gang tags sprayed on houses, stores and abandoned buildings, giving rural Indian communities an inner-city look.

Groups like Wild Boyz, TBZ, Nomads and Indian Mafia draw children from broken, alcohol-ravaged homes, like Mr. Wilson’s, offering brotherhood, an identity drawn from urban gangsta rap and self-protection.

Some groups have more than a hundred members, others just a couple of dozen. Compared with their urban models, they are more likely to fight rivals, usually over some minor slight, with fists or clubs than with semiautomatic pistols.

Mr. Wilson, an unemployed school dropout who lives with assorted siblings and partners in his mother’s ramshackle house, without running water, displayed a scar on his nose and one over his eye. “It’s just like living in a ghetto,” he said. “Someone’s getting beat up every other night.”