Whether we care to admit it or not, we are all tribalists to some degree. The way we dress sends social signals of tribal affiliation—think of a hipster and how he dresses and then think of someone who works for physical security for companies in the middle east and how he dresses. The values we embrace are communicated via virtue signaling in order to signal association with others. Even the decor used by a café indicates tribalism; signaling to customers who “we” are as a café and their branded coffee cups effectively signal membership in their tribe.
Starbucks doesn't sell coffee any more, they sell status symbols. i.e. "See me with my Starbucks cup." Very effective branding.— Michael Wright (@OilSlickCoffee) September 11, 2014
It’s human nature to associate with those who are similar to us. When one talks about community, they are talking about tribalism. A community is a group of people who all share defining characteristics, which include the immediate area in which they live. Community organizers organize tribes and this has a social function— it is a method for survival:
Tribalism has a very adaptive effect in human evolution. Humans are social animals, and ill-equipped to live on their own. Tribalism and social bonding help to keep individuals committed to the group, even when personal relations may fray. This keeps individuals from wandering off or joining other groups. (The Wikis)
Further, there seems to be a neurological basis for tribalism. From the same wiki article:
"[T]ribalism" is in some sense an inescapable fact of human neurology, simply because many human brains are not adapted to working with large populations. Once a person's limit for connection is reached, the human brain must resort to some combination of hierarchical schemes, stereotypes, and other simplified models in order to understand so many people.
Traditions are tribal signals; ‘we do it this way because our fathers and their fathers did it this way.’ Traditions, especially useful or pragmatic traditions help to maintain unity within the tribe by giving meaning and value to membership. They are a way to pass down knowledge and skill through the generations by instilling a dogmatic way of doing things; ‘we do it this way because it is the way of our people.’
In this sense, useful or pragmatic traditions have value and serve a purpose, but only as long as they don’t impede improvement. Once a better way is learned, it should supplant the old tradition in order to ensure the tribe improves over the generations. Failure to adapt meaningful and improved traditions is the source of backwardness within tribes, which eventually leads to their demise. My opinion of traditions is in direct relation to something I recently wrote, that Balinese farmers needed to want to improve.
Normal tribalism is neither bad nor good. It simply is something to understand and be aware of and doing so—understanding and being aware of tribalism—is a critical aspect of having a rich and rewarding life experience.