Had you answered with a "yes" to the question whether the tribals are saved due to ignorance, then your entire scriptures, its dogma and its contents are not a pre-condition to salvation. Had you answered with a "no" then it makes your dogma inadequate to address the salvation modes necessary to make it applicable for all modes of human existence.
You are assuming the answer is yes or no. In fact, you are assuming (it would seem arrogantly), that your question is an important, decisive, logical question. None of that is true.
metmom gave you a great answer. God will judge justly. He will do the most loving thing as he does the just thing. It won't be the least strain on Him. I know secondhand of instances that Muslims had visions or dreams where Christ appeared and they became Christians - despite having no Christians to communicate the Gospel and no Bible to read.
... but in the end, you ain't one of them. You've heard, rejected, and set yourself up as the moral judge of God - apparently.
ampu
And as I’ve pointed out - the question is fundamentally flawed to begin with. Salvation in an INDIVIDUAL response - not extended entire tribes. As you point out ampu- it is not the decisive logical question he likes to think of it as.