Tribalism: noun

  1. The organization, culture, or beliefs of a tribe.
  2. A strong feeling of identity with and loyalty to one's tribe or group.
  3. The state of existing in tribes; also, tribal feeling; tribal prejudice or exclusiveness; tribal peculiarities or characteristics.

I will be so bold as to say that tribalism is as inherent in human beings as any other human characteristic. Tribalism has existed since the beginning of recorded human history. Tribalism exists today from the most basic jungle cultures all over the world, to the most advanced cultures all over the world. The clash of tribal cultures is as natural to human beings as sex. Tribal clashes are recorded since man began keeping records. Simply look at the stories in the Old Testament of the Bible, tribal clash after tribal clash after tribal clash.