There is a large difference between tribalism and nationalism, especially modern nationalism.
Tribalism is about family. Your cousin is always right if he is in a conflict with a guy you are not related to. You hire your uncle, even if he sucks at the job and there are ten better candidates. Tribal societies are almost always unsuccessful, especially when competing with non-tribal societies.
Nationalism may look the same at first, but it is a much bigger category. Most of the people in my nation are ethnically related to me, but it is culture, language, and shared history that tend to bind national groups. A person who roots for someone of their own nationality is already a very broad-minded person. They have already gone outside the scope of family and probably class. Countries based on nationalism have been hugely successful, while those that are not, have not done nearly so well.
Internationalists tend to be elitists and anti-democratic. So while they come across as high-minded, in practice internationalism almost always is idealistic at best and more likely a justification for chauvinism.
