Wearing a traditional shirt with ribbons, Irving stood on a buffalo skin and was prayed over by a tribe elder, Vernon Iron Horse. As a drum group played and chanted, Irving was wrapped in a blanket, had an eagle feather tied into his hair along with a medicine ball made of porcupine quills, and had a beaded medallion placed over his head as his name was revealed to him.
Irving's older sister, Asia, was also part of the ceremony and was given the Lakota name Buffalo Woman.
"Our journeys have been directed in so many different ways, but yet we are still standing here embracing each other as if we haven't lost any time," Irving said. "It's really special for me to be here because I lost my mom at a very young age, and I had no idea about the history and how inclusive this group is and what it means to part of the Sioux tribe."
Irving's mother, Elizabeth Larson, was a descendant of the Standing Rock Sioux but was adopted out as a small child. Irving, whose mother died when he was 4, has known about his lineage and has recently starting embracing it publicly.
He stunned members of the tribe in 2016 when he said in an interview with ESPN that his mother was a member. That sent the elders scrambling to identify a lineage, and they found his grandparents and great-grandparents from the White Mountain family in the Standing Rock reservation in South Dakota.
Irving supported the tribe's fight against the Dakota Access Pipeline two years ago and has had the tribe's logo tattooed on the back of his neck. Earlier this year, he released a version of his Nike signature shoe that featured the logo as well. Last year, Irving made a six-figure donation to the tribe.
The tribe and Irving have been working since April to put together a time for him to come and take part in a naming ceremony, which is sacred in Native American culture.
"We're welcoming home two of our own," Standing Rock Chairman Mike Faith said. "This definitely is history."
The crowd of about 1,000 at the Prairie Knights Pavilion included local high school students, many of whom were wearing the Standing Rock version of Irving's shoes. There were also many of Irving's distant relatives in attendance, dozens of whom wore Celtics green shirts with his No. 11 and "Welcome home, Kyrie" on them.
Many members of the tribe have been adopted and left the reservation over the past several decades, and the tribe is hoping Irving will encourage others with Native American heritage to embrace their roots.
"We don't want our children to lose their identity," said Frank Jamerson, a former tribe council member. "We have their opening to the world. Other children of native heritage have the opportunity to come home."
After watching a display of traditional dance, Irving received a number of gifts from members of the tribe. Then he signed many autographs, shook hands and embraced hundreds of people in attendance. Irving said he plans to return to the reservation in the future and deepen his relationship with the tribe.
"I'm with you guys forever," Irving said. "I hope you don't mind that."