The Roman Republic was no model for peace and tranquility either - especially in its last days. The Venetian Republic may have been better. Maybe not.
The fact is human beings - and human society - are contentious and turbulent by nature.
From Funk and Wagnalls College Dictionary
Democracy (demos=people + krateo=rule) A theory of government which, in its purest form, holds that the state should be controlled by all the people...
Repbulic (res=affair + publica=public, of the people) A state in which the sovereignty resides in the people or a certain portion of the people; a representative democracy...