[Definition] Rule by a government based on small complex society of varying degrees of centralisation that is led by an individual known as a chief. [Term] 
Chiefdom (Tribal)
A d h o c r a c y
B a n d s o c i e t y
B u r e a u c r a c y
C h i e f d o m ( T r i b a l )
C y b e r s y n a c y
P a r l i a m e n t a r y s y s t e m
P r e s i d e n t i a l s y s t e m
N o m o c r a c y