The United States has over 500 native american tribes. But there are also many foreign people groups from tribal cultures that have come to live in the United States. They too must be evangelized and discipled. Who will go and work with this people? The live in 10 different countries other than their native Vietnam where they are 16% evangelical and Laos where they are only 1% Christian. There are countries even in the West where they are totally unreached. See database shown below and also the video.