> I hate stuff like that hostility between Hopi and Navajo people though. If anything, learning a neighbor's language tends to bring people together!

I tend to agree, but I also respect the wishes of the various groups. They've undergone experiences at the hands of colonizers that I can't begin to imagine, and if they want to try to preserve something of their culture so that it stays in their culture, and not just let any outsider with a passing interest learn it, I support them in that. Though I do wish more were like the Cherokee Nation, which offers free online courses for anyone across various levels of Cherokee, also integrating culture and such.