Amazonian tribes tend to die off not long after being introduced to the modern world:
It’s still happening today in Brazil, where 238 indigenous tribes have been contacted in the last several decades, and where between 23 and 70 uncontacted tribes are still living. A just-published report that takes a look at what happens after the modern world comes into contact with indigenous peoples isn’t pretty:
Of those contacted, three quarters went extinct. Those that survived saw mortality rates up over 80 percent. This is grim stuff. “Our analysis dramatically quantifies the devastating effects of European colonization on indigenous Amazonians. Not only did ~75 percent of indigenous societies in the Brazilian Amazon become extinct, but of the survivors, all show evidence of catastrophic population declines, the vast majority with mortality rates over 80 percent,” writes Marcus Hamilton of the University of New Mexico in a paper published in Scientific Reports. …
Sure, people don’t go in and kill entire tribes directly, they offer indigenous people the chance to assimilate into modern culture. But, as Hamilton notes, the trappings of modern society—access to better healthcare, technology, and education—haven’t improved tribes’ overall outcomes.