Year Zero (political notion)
The term Year Zero (Khmer: ឆ្នាំសូន្យ chhnam saun), applied to the takeover of Cambodia in April 1975 by the Khmer Rouge, is an analogy to the Year One of the French Revolutionary Calendar. During the French Revolution, after the abolition of the French monarchy (September 20, 1792), the National Convention instituted a new calendar and declared the beginning of the Year I. The Khmer Rouge takeover of Phnom Penh was rapidly followed by a series of drastic revolutionary de-industrialization policies resulting in a death toll that vastly exceeded that of the French Reign of Terror.
The idea behind Year Zero is that all culture and traditions within a society must be completely destroyed or discarded and a new revolutionary culture must replace it, starting from scratch. All history of a nation or people before Year Zero is deemed largely irrelevant, as it will ideally be purged and replaced from the ground up.