*major sips coffee slowly *

No tribe, part of formaly the Army of a nation state, or you could say a large group of tribes under one leader and gathered under one flag, one goal, now known as the Enclave.
 
we are a professional force, trained under arms at all times, acting as offensive and defense forces for our nation.

*Thinks trying to explain it*
a ... Warrior Caste... we serve, the others of nation tithe food, resources, and recruits in exchange for protection.