TAHLEQUAH, Okla. — Cherokee children were disappearing.

At weekly staff meetings, Todd Hembree, the attorney general of the Cherokee Nation, kept hearing about babies in opioid withdrawal and youngsters with addicted parents, all being removed from families. The crush on the foster care system was so great that the unthinkable had become inevitable: 70 percent of the Cherokee foster children in Oklahoma had to be placed in the homes of non-Indians.

“We have addicted mothers and fathers who don’t give a damn about what their children will carry on,” said Mr. Hembree, a descendant of a revered 19th-century chief. “They can’t care for themselves, much less anything else. We are losing a generation of our continuity.”

Across the country, tens of thousands of people are dying from abuse of prescription opioids. Here in the capital of the Cherokee Nation, the epidemic is exacting an additional, deeply painful price. The tribe’s carefully tended heritage, traditions and memories, handed down through generations, are at risk, with so many families now being ruptured by drugs.