Federalism
Federalism is a non-quadrant system that combines multiple regional governments into one central or "federal" government. The main characteristic is the equivalence between the two or more levels of government. Nowadays, a federal government is inherently 
democratic in order to share power between governments.
History
The earliest known implementation of a federalist government was the Achaean League in Hellenistic Greece, which lasted from 280 to 146 BC. It had three governments: an assembly of citizens (synodos), a small council (boule), and a general (strategos), who had a board of ten officials. The general controlled the military and the council made the decision making. However, the system was not fully democratic, as it is likely the council was controlled by the wealthy due to the difficulty to travel to the usual meeting place.
Philosopher Immanuel Kant believed that a federalist society was possible with a constitution and a system of checks and balances. This model has been used for numerous federal systems across the world. Some of the most notable include the United States, Brazil, Russia, India, and Nigeria.
