Archaeological evidence indicates that the Mekong delta and its immediate environs have been inhabited since at least 4000 BCE. Whilst the exact origins of the ethnic Khmers is still a subject for debate, they are believed to have migrated to the area along with their Mon cousins from either south west China or north east India in around 2000 BCE. Certainly their presence in what is now Indochina substantially predates the arrival of the ancestors of today's Thai, Lao and Việt peoples.

Early in the first millennium CE, both India and China began to establish trading contacts in the region. Indian influence was particularly strong in the Mekong basin area, and over successive centuries Khmer political institutions and culture progressively took on board Indian ideas and practices regarding kingship, law, religion, art, architecture, literature, language and writing.

The kingdom of Funan – the first Shivaite Hindu state in South East Asia – was established in the lower reaches of the Mekong River between the 1st and 3rd centuries CE. Between 550 and 680 this kingdom became integrated with one of its former vassal-states, resulting initially in the formation of two interlinked kingdoms – Water or Lower Chenla, centred at Angkor Borei near the mouth of the Mekong River, and Land or Upper Chenla, which incorporated a large area from modern Kompong Thom Province into what is now the southern Lao province of Champassak. Thereafter these two kingdoms began to develop into a unified Khmer state, but a dynastic dispute in the early 7th century brought renewed division and civil war, leaving the Khmers severely weakened in the face of subsequent incursions into the region by the powerful Javanese Seilendra dynasty. During this period the Javanese occupied both parts of Chenla, seizing members of the Khmer ruling family and taking them back to Java.

At the beginning of the ninth century, the kings set up their respective capital in the present province of Siem Reap. For nearly six centuries, the kings enriched it by building temples one after another and each being more sumptuous than the other. Two hundred of these temples are spread all over in the Angkorian area some 400 square kilometers in the Siem Reap Province. The temples and their sanctuaries are best known for their architecture and sculptures.

It started with the return from Java in 802 of Jayavarman II, founder of the Angkor kingdom, was a turning point in Khmer history; he had spent his formative years at the Seilendra court and proceeded to transplant to his new kingdom many of the traditions associated with the cult of the powerful god-king or devaraja, which had already reached a high degree of development in Java. This cult identified the monarch with Vishnu’s earthly incarnation Rama, depicted by ancient Indian epics such as the Ramayana as a heroic figure imbued with righteous kingship. The prosperity of the Khmer empire was founded on a sophisticated irrigation and hydraulic system centered on the Great Lake (Tonle Sap) and the middle Mekong. This eventually became so extensive and efficient that, at its height, it is believed to have supported a population of around one million people in the area surrounding Angkor. Utilizing this vast reservoir of manpower, the Angkorian kings constructed a vast network of magnificent temple complexes, the architecture of which reflected their claims to be earthly incarnations of the Brahman gods.

It is understandable that the country was exhausted after these enormous efforts. The decline of the Angkor era began in the 13th century after the death of King Jayavarman VII. Due to Siamese invasion and the limitations of the irrigation system, Khmer power declined so drastically that the king was finally obliged to move to the vicinity of Phnom Penh in 1431. The four centuries which followed were an undistinguished period in Cambodian history, as successive kings sought to steer a course between their more powerful neighbors Siam and Đại Việt (later Việt Nam), turning ultimately for protection to the French in 1863, who established a foothold in Sài Gòn during the late 1850s.

Whilst it could be argued that French colonial rule saved Cambodia from being apportioned between Siam and Viet Nam (indeed, in 1907 the French did secure the return of the westernmost provinces of Battambang and Siem Reap, which had been held by Bangkok since 1794), little was subsequently done to develop the country by the colonial administration, which brought in Vietnamese to run the civil service whilst playing off one branch of the Khmer royal family against another.

Cambodian nationalism began to emerge in the wake of the crowning of the 18 year-old Norodom Sihanouk as king in 1941, when the events of World War II made it apparent just how tenuous the French grip on Indochina actually was. The French returned in 1945 following the surrender of occupying Japanese forces, but by the early 1950s, preoccupied with the war in Việt Nam, they began negotiations with King Norodom Sihanouk, leading in 1953 to the country's recognition as an independent state. Two years later the king abdicated the throne to run for public office, which he was to hold until his overthrow in 1970.

Whilst the Sangkum Reast Niyum (‘Popular Socialist Community’) period of 1955-1970 is often remembered as an era of peace and prosperity, the combined effects of a deteriorating economic situation and serious ethnic tensions in the two decades after independence created deep-rooted divisions in Cambodian society, leading to the growth of popular support for the communist Khmer Rouge. Prince Sihanouk's decision during the 1960s to support the communists in neighboring Việt Nam and to allow North Vietnamese forces to use Cambodian territory as an extension of the Hồ Chí Minh trail incurred American wrath and ultimately led to his overthrow in 1970 by former army chief-of-staff Lon Nol. However, the new government proved heavily dependent on American support and ultimately fell in 1975 when US involvement in Indochina finally came to an end.

Sadly, the Kingdom of Cambodia is best known today not for the cultural refinements and sophistication of the Angkorian era, but for the excesses of the Khmer Rouge government which held power between 1975 and 1979.

As soon as they had taken control of the country the forces of Khmer Rouge leader Pol Pot sought to implement a radical restructuring programme aimed at transforming Cambodia into a Maoist, peasant-dominated agrarian co-operative. The calendar was reset at 'Year Zero'; currency was abolished and postal services suspended; all links with the outside world (except for one fortnightly flight to Beijing) were cut; and the entire population of Phnom Penh and the provincial towns was evacuated to the countryside to work in the fields. Over the next four years it is estimated that over 1.5 million people lost their lives, including most of the country's skilled and educated citizens, and even after the overthrow of the Khmer Rouge by the Vietnamese in 1978-9 a further 10 years of intermittent civil war was to follow, serving only to prolong the social, economic and infrastructural devastation.

Following the withdrawal of Vietnamese forces from Cambodia in 1989, talks were convened by the French government with the aim of resolving political differences within the country. The Paris Peace Accord which followed in 1991 led to the establishment of the State of Cambodia. A UN force known as the United Nations Transitional Authority Commission (UNTAC) was subsequently established and in May 1993, supported by the presence of some 22,000 UN troops, a general election was held. Thereafter Cambodia once more became a monarchy, with King Norodom Sihanouk as Head of State, four decades after his abdication.

The Cambodian People’s Party (CPP) and Funcinpec entered into a power-sharing arrangement under their respective leaders, Hun Sen and Prince Ranariddh, but the new government was fraught by problems, leading eventually to the upheaval of 1997 in which Funcinpec was ousted from government. Since the general election of 1998, Hun Sen has held the post of Prime Minister, with opposition leader Prince Norodom Ranariddh (Funcinpec) as Chairman of the National Assembly.

Cambodia became a full member of the Association of South East Asian Nations (ASEAN) in April 1999, an event seen by many as marking the country’s coming of age as a member of the international community. More recently in 2004, Cambodia acceded to the World Trade Organisation, becoming one of the least developed nations to join its ranks.

In the general election of August 2003, the CPP won but failed to gain a clear two-thirds majority as required under the Cambodian constitution in order for it to form a new government. The subsequent stand-off between the leading political parties of the CPP, Funcinpec and Sam Rainsy Party was only resolved in July 2004 following various defections and horse-trading between parties, and with the creation of a larger cabinet providing high-ranking positions to many CPP and Funcinpec stalwarts.

In October 2004, King Norodom Sihanouk abdicated the throne due to ill health, ending his reign of 60 years. His son, Norodom Sihamoni, was crowned on 29 October in Phnom Penh, with ancient Buddhist and Brahmanist rituals and street celebrations lasting three days. The new king is a former classical dancer who lived in Prague and Paris for many years, most recently serving as Cambodia’s ambassador to UNESCO. He is widely viewed as apolitical, and may yet prove to be an influence for peace and unity in Cambodia.

After regaining Independence in 1953, the country resumed several names:

1. The Kingdom of Cambodia (under the Reachia Niyum Regime from 1953 to 1970)
2. The Khmer Republic (under the Lon Nol Regime from 1970 to 1975)
3. Democratic Kampuchea (under the Pol Pot Genocidal Regime from 1975 to 1979)
4. The People's Republic of Kampuchea (1979-1989)
5. The State of Cambodia (1989-1993)
6. The Kingdom of Cambodia (1993 until now)