Somewhere over the Mekong Delta we crossed from Vietnamese into Cambodian airspace. It’s only a 40-minute flight from Ho Chi Minh City to Phnom Penh but it spans one of the most historically volatile regions in all of Southeast Asia. Back in the 18th century, before the Vietnamese annexed it, the rich agricultural land of the Delta was part of the Khmer Kingdom. Since then Cambodia’s border has been buffeted by war, violated by its Thai and Vietnamese neighbours, and ignored by foreign powers.

As we begin our descent into Phnom Penh I get a fleeting glimpse of the mighty Mekong River that runs through the centre of the city. Moments later a friendly immigration officer welcomes us to Cambodia and takes only a few minutes to process our visas. Kosal, a stocky, dark skinned fellow in his early 40s greets us with a big smile. He will be our guide in Phnom Penh. The trip to our hotel takes us past stately French Colonial houses, some restored, others crumbling into ruin. Built 100 years ago when Cambodia was part of French Indochina, they now stand side by side with Art Deco mansions that once belonged to officials of Prince Norodom Sihanouk’s pre revolutionary government.

The traffic, a mix of tuk tuks, motorbikes, and pickups, is less frantic than that in Ho Chi Minh and, perhaps because it is smaller, the pace of life seems more relaxed. After a sumptuous dinner at the Amoc Cafe we return to the Juliana Hotel, order a drink from the bar, and settle down at a table in the lush poolside garden. It’s hard to imagine that 33 years ago foreigners like us were banned from the country and the people of Phnom Penh were fleeing their city in terror, abandoning their homes, shops, and most of their possessions to a handful of Khmer Rouge soldiers.

In her book First They Killed My Father (Harper Collins), Loung Ung describes the day the soldiers arrived and ordered everyone to leave on the pretense that the U.S. was about to bomb the city. “You can return in three days,” they were told. It was the first of many lies designed to control the terrified people. At checkpoints outside the city the Khmer soldiers offered good jobs to anyone who had worked for the Lon Noi government. Those who identified themselves were killed. The others became virtual slaves in work camps and rural communes where many died of starvation and disease.

I asked Kosal if he remembered that terrible time. “Yes,” he replied, “my experience was very similar to that of Loung Ung. Almost every family in Cambodia was affected one way or another by Khmer Rouge violence. They killed three members of my family and I have lost track of the others.”

The convoluted history that paved the way for the Khmer Rouge takeover and the subsequent tragedy of Pol Pot’s social experiment is a tale of political intrigue, deceit and social collapse. Cambodia gained independence from France in 1953 and for 20 years, under the autocratic rule of Norodom Sihanouk, it enjoyed a period of relative prosperity.

But discontent with Sihanouk’s repressive policies came to a head in 1970 when a military coup led by general Lon Noi overthrew him. After fleeing to Beijing Sihanouk set up a government in exile allied with a revolutionary movement lead by Pol Pot, whose peasant army had been waging a limited guerilla war against the government since 1963. Sihanouk nicknamed them the Khmer Rouge and his support drew thousands of new recruits into the revolution.

In the meantime the Vietnamese war was spilling over the border, and in 1969 U.S. president Nixon authorized the secret bombing of suspected communist bases in Cambodia. Over the next four years an estimated 250,000 Cambodian civilians, mostly peasants, were killed by B52 carpet-bombing. The survivors, bitter and displaced from their land, flocked to join the Khmer Rouge and, with aid from China, Pol Pot’s guerrilla skirmishes escalated into full-scale civil war. On the 17th of August 1975 truckloads of Pol Pot’s Khmer Rouge soldiers stormed triumphantly into Phnom Penh and replaced the Lon Noi government with a regime even more brutal and horrific than the war that brought them to power.