The region of Cambodia was the centre of the culturally-advanced Khmer Empire that flourished from the 5th to the 12th century. Today, over one million visitors a year marvel at the Angkor ruins.
Cambodia achieved full independence in 1954, but in 1970 a bloodless coup saw the formation of the Khmer Republic. Five years later, the Khmer Rouge, led by the infamous Pol Pot, seized control and renamed the country Democratic Kampuchea. It was the start of one of the horrid episodes of humanity.
By 1979 the madness was ended and the People's Republic of Kampuchea was established. The name changed to State of Cambodia in 1990, and Kingdom of Cambodia three years after that.
Cambodia on Wikipedia