Below is “Appendix B: The 1900-Year Countdown to UNTAC” from  Cambodia and the Year of UNTAC.
To help readers get the big picture I have annotated it with the major dates of Loung Ung’s  First They Killed My Father. Those dates are in red.  I’ve added a little about myself, in blue.

THE 1900-YEAR COUNTDOWN TO UNTAC

First century A.D.: What Cambodians like to call the first Khmer kingdom comes into existence. There is extensive trade with China and India, with Indian religion, arts and the bureaucratic elite making strong impressions.

Ninth century: Classical Khmer architecture is firmly established under the reign of Jayavarman II (reigns 802-850).

Tenth century: Yasovarman (reigns 889 to 910) moves his capital to Siem Reap where he founds the first city of Angkor. Except for brief intervals, the capital remains there for four centuries.

Twelfth century: At the height of the Khmer Empire, Suryavarman II (reigns 1112 to 1152) builds Angkor Wat, the masterpiece of Khmer architecture. His armies range into much of present-day Thailand and Vietnam.

Late twelfth century: Jayavarman VII (reigns 1181 to 1201) builds the last of the great Khmer buildings, Bayon, the center of Angkor Thom, near Angkor Wat.

1369, 1388, and 1431: The Thais repeatedly capture Angkor.

1434: The capital shifts to Phnom Penh.

Sixteenth century: Thais and Vietnamese begin to shrink the Khmer Empire.

End of 18th century: Cambodia is reduced to a buffer state between Vietnam and Thailand.

1863: King Norodom I (reigns 1859 to 1904) consents to let Cambodia become a French protectorate.

1908: French begin reconstruction of Angkor Wat, which has been virtually lost in the jungle. French also piece together Cambodian history by translating ancient inscriptions.

1941: Norodom Sihanouk becomes King of Cambodia.

1945: French resume control at the end of World War II.

1951: Khmer People’s Party, the first Cambodian communist party, forms. Members of this party will later be claimed as founding fathers by both the Khmer Rouge and the CPP, the party that evolved out of the Vietnamese-installed Phnom Penh government.

November 9, 1953: Cambodia declares independence.

May 1954: At the Geneva conference, the French agree to withdraw from Cambodia.

March 1955: Norodom Sihanouk abdicates the throne and his father, Norodom Suramarit, becomes king. Sihanouk becomes premier after a general election in September.

1960: King Norodom Suramarit dies and Prince Norodom Sihanouk becomes head of state, but not king.

1963: Sihanouk accuses the U.S. Central Intelligence Agency of fostering rebellion in Cambodia and renounces all U.S. economic, military, and cultural aid.

1965: The U.S. has 300,000 troops stationed in Vietnam. Cambodia breaks diplomatic relations with Washington.

1966: For the first time in eleven years, members of the Cambodian National Assembly are elected from among candidates not personally selected by Sihanouk.

1969: The U.S. begins massive bombing of the Ho Chi Minh trail that runs through Cambodia.

March 18, 1970: With what Sihanouk suspects is U.S. government help, he is pushed out of office, and what many Cambodians consider the golden age of modern Cambodia comes to an end.

April 17, 1970 Loung Ung, author of “First They Killed My Father” and other books is born in Phnom Penh.

April 30, 1970: American President Richard Nixon announces that American forces have staged an “incursion” into Cambodia to attack North Vietnamese sanctuaries. Huge anti-war demonstrations erupt across the United States with four students shot by National Guard troops at Kent State University. The incursions last until July.

Late 1970: American troop strength in Vietnam is down to 280,000 from a high of 540,000 in 1968.

1972: Two million Cambodians are made homeless by the war in Cambodia.

March 29, 1973: Last American troops leave Vietnam.

August 6, 1973: An American B-52 bomber mistakenly drops its load of bombs on its ground-based radar beacon, instead of the target coordinates, and wipes out most of the Mekong ferry port of Neak Luong.

August 14, 1973: Americans stop bombing Cambodia.

April 12, 1975: The American Embassy staff evacuates Phnom Penh by helicopter. Most Cambodian cabinet members and embassy staff, who are offered a way out, decide to stay in Cambodia.

April 17, 1975: The Khmer Rouge enter Phnom Penh and the Lon Nol regime collapses. Year Zero begins with the “Angka,” as Pol Pot calls his movement, turning back the clock in Cambodia as the cities are emptied in a move to “pure” communism. Loung Ung is five years old; she and her family leave Phnom Penh.

April 29, 1975: The U.S. ambassador to Vietnam leaves Saigon as the last Americans are evacuated. Thousands of Vietnamese flee Vietnam in a chaotic exodus. Over fifty thousand Americans have died in the Vietnam war.

April 30, 1975: The North Vietnamese enter Saigon and the government of South Vietnam surrenders.

December 25, 1978: Vietnam invades Cambodia.

January 7, 1979: The Vietnamese “liberate” Phnom Penh, and the Khmer Rouge regroup in the dense jungles near the Thai border. The “People’s Republic of Kampuchea” is installed by the Vietnamese, with former Khmer Rouge military men, who earlier fled the Khmer Rouge to Vietnam, in charge. Cambodia’s seat at the UN continues to be occupied by the Khmer Rouge, as the world body refuses to recognize the Vietnamese-installed government in Phnom Penh. After 1982, the seat is taken by the Coalition Government of Democratic Kampuchea, which includes Sihanouk. The United States leads an economic embargo of Cambodia and Vietnam.

October 5, 1979: The first aid donations arrive at the Thai-Cambodian border in response to the massive rush of Khmer refugees. Over the next thirteen years, over half a million Cambodians will enter Thailand. Many will succeed in re-settling overseas while 370,000 others will eventually be returned to Cambodia.

October 14, 1979: First international airlifts of relief supplies to Phnom Penh begin.

October 22, 1979: Thais announce the creation of the Khao I Dang Holding Center in Thailand for Cambodians being considered for resettlement in third countries. Loung Ung leaves Cambodia for Vietnam that same month.

February 1980 Loung Ung and two family members reach the Lam Sing refugee camp on the coast of Thailand. 

April 6, 1980: The Phnom Penh government reintroduces the riel as the standard currency of Cambodia.

June 1980 Loung Ung and two family members leave Thailand for the U.S.A. She is ten years old.

1982: The United Nations declares the emergency in Cambodia to be over and Western aid to Cambodia is reduced. This results in economic and political stagnation for Cambodia. For more on this see Eva Mysliwiec’s aptly entitled Punishing the Poor: The International Isolation of Kampuchea.

1981: The author, Tom Riddle, begins work in the Philippines Refugee Processing Center in Panat Nikhom, Thailand. With a population of about 20,000 refugees, the average stay is about six months–long enough for the refugees to “be processed” for life in the West and be taught some basic survival skills: how to get a job, open a bank account, etc. In 1982, Tom goes to Thailand and works in the Panat Nikhom Refugee Processing Center for three years.

Early 1985: Vietnamese troops push Khmer Rouge and opposition forces across the Thai border and into “border camps” in Thailand. The Khmer Rouge regroup deeper in the Pailin area of Cambodia.

Late 1985: Site Two refugee camp becomes the largest concentration of displaced Cambodians on the Thai-Cambodian border.

Late 1985: Tom Riddle returns to the USA, but returns to work in the Panat Nikhom Refugee Processing Center during the summer breaks from graduate school.

September 1989: Vietnam claims it has withdrawn all of its troops from Cambodia, thus offering the first hope of an international settlement. Pol Pot resigns as military commander of the Khmer Rouge, but is still believed to be “Brother Number One,” the guiding force behind all KR activities.

1990: Aid to Cambodia from Vietnam, the Soviet Union, and the Eastern bloc ends, and more international organizations and embassies open in Phnom Penh.

October 23, 1991: The five permanent members of the United Nations Security Council, as well as Australia, Indonesia, Japan, and other countries, joined by Prince Norodom Sihanouk and the four factions representing jointly the people of Cambodia, agree on a framework and process for peace in Cambodia and sign “The Agreement on a Comprehensive Political Settlement of the Cambodia Conflict.” The agreement provides for a cease-fire, the withdrawal of all foreign forces from Cambodia, the return of the estimated 370,000 refugees, the release of the prisoners of war, and the reconstruction and rehabilitation of the country. “Phase II” of the agreement requires the forces of the four factions—the State of Cambodia (SOC), the Khmer People’s National Liberation Front (KPLNF), the United Front for an Independent, Neutral, Peaceful and Cooperative Cambodia (FUNCINPEC), and the Party of Democratic Kampuchea (PDK)—to regroup, canton their forces under UNTAC supervision, and surrender their arms.

October 23, 1991: Sihanouk returns to Phnom Penh.

January 1992: The U.S. economic embargo of Cambodia ends.

March 15, 1992: Yasushi Akashi arrives in Cambodia and UNTAC officially begins.

March 22, 1992: The author arrives in Cambodia.