1975 in Cambodia in the context of "Year Zero (political notion)"

Year Zero (Khmer: ឆ្នាំសូន្យ, Chhnăm Sony [cʰnam soːn]) is an idea put into practice by Pol Pot in Democratic Kampuchea that all culture and traditions within a society must be completely destroyed or discarded and that a new "revolutionary" culture must replace it starting from scratch. In this sense, all of the history of a nation or a people before Year Zero would be largely deemed irrelevant, because it would ideally be purged and replaced from the ground up.

The first day of "Year Zero" was declared by Angkar and the Khmer Rouge on 17 April 1975 upon their takeover of Cambodia to signify a rebirth of Cambodian history. Adopting the term as an analogy to the "Year One" of the French Revolutionary Calendar, Year Zero was, in effect, an attempt by the Khmer Rouge to erase history and reset Cambodian society, removing any vestiges of the past.