A quick look through Ethnologue — and really the application of common sense — shows that the majority of these languages are tribal languages. Many of these languages are dying as the result of an ever-increasing marginalization by governments and further back, in colonial countries, as a result of years and years of belief by colonial powers in the concept of “The White Man’s Burden.”*
*This concept is derived from the Rudyard Kipling poem of the same name, which, until I went looking for a reference for you, I never actually knew. Up until now, it had just been a term I learned in world history in high school. I find it a little ironic that a man born in a colonized country should have shilled for imperialism.