The Kingdom of Cambodia, also known as the First Kingdom of Cambodia, and commonly referred to as the Sangkum period, refers to Norodom Sihanouk's first administration of Cambodia from 1953 to 1970, an especially significant time in the country's history. Sihanouk continues to be one of the most controversial figures in Southeast Asia's turbulent and often tragic postwar history. From 1955 until 1970, Sihanouk's Sangkum was the sole legal party in Cambodia.

The Khmer Republic was a Cambodian state under the United States-backed military dictatorship of Marshal Lon Nol from 1970 to 1975. Its establishment was formally declared on 9 October 1970, following the 18 March 1970 coup d'état which saw the overthrow of Norodom Sihanouk's government and the abolishment of the Cambodian monarchy.