If you're asking about the moral aspects of forcing them into society, there are different approaches you could look at:
In general, social contract theories assume that the act of joining society has to be 1) voluntarily 2) out of self-interest 3) based on strict reciprocity. As society makes demands on you, your rights and your behaviour, it seems plausible that you should have to agree to that in advance. We would then conclude that they do have the right to remain outside the society. You can find that thought expressed in the three major social contract theories, namely the Leviathan, Locke's Treatises and Rousseau's Social Contract.
A different example is Kant, who claimed that there's a moral obligation to leave the state of nature and that one may use force to make others join a legal state. There must be a legal relation between all human beings who could interact with one another or have influence on others (which, today, is pretty much everyone). According to Kant, they would not have a right to remain the way they are then, and in fact, I think that's plausible: They demand property and to be left alone. These claims are dealt with legally, and as soon as they are legal persons, they are part of society. Of course the native tribe (e.g.) is a society in itself. The "problem" is that Kant claims that the same applies to communities/states. They, too, need a legal relation to deal with differing interests. You can find some details here or in the first part of Metaphysics of Morals. On the relation between states, have a look at The Perpetual Peace, a very interesting short book.
This are just two examples how your question could be answered, I bet there are other approaches I didn't think of. I wish to add that, whether we agree with these approaches or not, I find them much more satisfying than an answer that is based purely on rational considerations.