tribalism

from WordNet (r) 3.0 (2006)

tribalism
    n 1: the state of living together in tribes
    2: the beliefs of a tribal society

from The Collaborative International Dictionary of English v.0.48

Tribalism \Trib"al*ism\, n.
   The state of existing in tribes; also, tribal feeling; tribal
   prejudice or exclusiveness; tribal peculiarities or
   characteristics.
   [1913 Webster]