gangs develop primarily in two contexts -

....gangs develop primarily in two contexts - first, in the slum or ghetto where privacy as a counterpart of the manor can't be had and a reversion takes place to the wild state, with pack hunting and the patrolling of an actual physical patch of ground; and second, in the armed services, where the gang is dignified by being called a 'regiment' or some other hifilutin dirty word but here the reversion to the wild state is deliberately fostered by deprivation of privacy (barracks accommodation) and deprivation of property (you don't wear the clothes you chose and bought, you wear a uniform which belongs to the US!!!).

p.76 of John Bruner's Stand on Zanzibar (1968)