At sunset the basketball courts near the powwow grounds are a mess of beer cans, trees tagged with gang symbols, and trash stuck in the chain-link fence. Marty Red Cloud and two friends, Daniel Standing Soldier and Steve Yellow Boy, are regular players here. There are other courts closer to where they live, but the Tre Tres, one of about a dozen gangs on the Pine Ridge Reservation in South Dakota, often start trouble up there, so Marty and his friends tend to avoid them. A few days ago Daniel was hanging out in Marty's front yard while Marty ran an errand. Daniel says a few Tres spotted him and attacked him, breaking his hand with a bat.

At sunset the basketball courts near the powwow grounds are a mess of beer cans, trees tagged with gang symbols, and trash Marty, a 22-year-old high-school dropout, belongs to a gang called the Wild Boyz. A few years ago they were what cops called the peewees, a few ambitious teens who had split from a larger adult gang, the Nomadz, to forge their own identity. The Nomadz were heavily involved in coke dealing and prone to fighting, but many of them have "aged out" of gang life, meaning they've either started families, gone to prison, or simply died from drugs, violence, or drunk driving. Meanwhile, the Wild Boyz, with about 60 members, are poised to become the most influential and possibly the most dangerous gang in town.

"Everybody think they got to prove something," Marty says, rolling a thin joint on a wooden bench while Daniel shoots baskets and Steve plays defense. "Think they gotta be stronger than us, but they can't, because they need alcohol to give them courage. They can't just step up."

A beat-up Camry slowly cruises past the basketball court. The front grill is crumpled and somebody has smashed the windows, a typical act of gang retribution. The guys inside glare at Marty and his friends, and the ball stops bouncing as they stare back. "Pussy Tres," Marty says as the car glides past. "See what I'm saying? Ain't gonna do shit long as we together—and they ain't drunk yet."

Most Pine Ridge gang members take their style from hip-hop, wearing do-rags, XXL tees, and college-basketball jerseys. Marty isn't like that. He has a faint Fu Manchu and a wispy goatee that crests like a wave under his acned chin. He wears his Wild Boyz colors—black, white, and gray—subtly, in the form of Raiders shirts or other clothes. Most of the gangs on the rez ape national gangs such as the Bloods and the Crips, and will even borrow their names. The Wild Boyz seem to have no connection to any other gang; they're a pure product of Pine Ridge.

"Our clique is about our culture," he says, "about being a man, and a warrior." Marty is the great-great-great-grandson of a Lakota chief named Red Cloud, a famous warrior and statesman. In 1866, Red Cloud began to beat back the U.S. Army as it was building forts in the heart of Lakota country in present-day Wyoming. He helped secure treaties for the Indians and was the man who settled the tribe here in Pine Ridge. Marty's grandfather, Oliver Red Cloud, is the chief of the Oglala Sioux.