Cambodia became a protectorate of France in 1863, and was made part of the French Indochina Union in the 1880s. Cambodia gained independence from France in 1953, and the country became the Kingdom of Cambodia under King Sihanouk, who became prime minister in 1955 and head of state in 1960. Sihanouk had stable control of the country until the mid-1960s, but as the Vietnam War intensified after 1965, the political conditions in Cambodia became more complicated.
By 1970, the Cambodian monarchy was abolished and the Southeast Asian country was proclaimed to be the Khmer Republic. Following a five-year struggle, Communist Khmer Rouge forces captured Phnom Penh in 1975 and ordered the evacuation of all cities and towns; over 1.7 million people died from execution, starvation, disease or enforced hardships. A 1978 Vietnamese invasion drove the Khmer Rouge into the countryside and touched off more than a decade of fighting.
The 1991 Paris Peace Accords mandated democratic elections and a ceasefire, which was not fully respected by the Khmer Rouge. UN-sponsored elections in 1993 helped restore some normalcy under a coalition government. Factional fighting in 1997 ended the first coalition government, but a second round of national elections in 1998 led to the formation of another coalition government and renewed political stability. The remaining elements of the Khmer Rouge surrendered in early 1999.
In October 2004, the Cambodian National Assembly ratified an agreement with the United Nations on the establishment of a tribunal to bring genocide charges against Khmer Rouge leaders, and the tribunal opened its first trial in March 2009. Since 1999, as peace resumed after three decades of war and unrest, the country has made significant progress in economic performance. However, Cambodia remains one of the poorest countries in the world, as decades of war and internal conflict have ruined the physical, social, human, and economic foundations necessary for growth and development.