Little is known about prehistoric Cambodia and the origin of the Khmers. Probably they came from the north, down the Mekong river. They migrated into Southeast Asia, being pushed down by invading Sino-Tibetans from the north.
In a Cambodian legend, the naga were a reptilian race of beings who possessed a large kingdom in the Pacific Ocean. The Naga King's daughter married an Indian Brahmana named Kaundinya, and from their union sprang the Cambodian people.
Therefore still Cambodians say that they are "Born from the Naga".
Funan is the earliest known kingdom in the Mekong Delta, established in the first century in the south of present Vietnam. At its height, Funan covered much of mainland Southeast Asia, including modern day Cambodia and Southern Vietnam, as well as parts of Laos, Thailand and Myanmar, and even extending into the Malay Peninsula. Funan was a rich kingdom because of trade and agriculture.
It was an important stopping place for traders from India who were on their way to southern China. This explains the strong Indian influence in Cambodian culture (see People and Culture).
Exports from Funan were largely forest products and precious metals—including gold elephants, ivory, rhinoceros horn, kingfisher feathers, wild spices like cardamom, lacquer hides and aromatic wood.
The Funan Kingdom existed for centuries, along with other Khmer kingdoms, who alternately worked together and fought each other. Some of Funan's former capital and major cities can now be seen as ruins at Samrong Sen, Angkor Borei, Ba Phnom, and Sophas in Cambodia and Oc Eo in what is now Vietnam.
In the sixth century the importance of Funan fell, largely because of distant events: the collapse of the Roman Empire and subsequently trade routes between the Mediterranean and China.
That gave rise to Funan’s vassal state Chenla. This Khmer Kingdom achieved its independence and eventually conquered all of Funan, absorbing its people and culture.
After the death of king Jayavarman I in 681, turmoil came upon the kingdom and at the start of the 8th century, the Chenla broke up into many principalities. There were two Chenlas, a land or upper Chenla and a water or lower Chenla.
The former was united and centered around the ancient territories of Chenla, while the latter consisted of several in the area that once constituted Funan.
During this time Javanese rulers extended their influence into Southeast Asia.
The rise of the Khmer Empire
King Jayavarman II was the founder of the Khmer kingdom. He was a Khmer, but lived long in Java. After his return, he quickly built up his influence, conquered a series of competing kings, and in 802 declared his kingdom independent from Java. He gave himself the title "divine king" and called his kingdom Kambuja. Initially it appeared the new kingdom would not be very powerful. Various kings fought each other to the death.
King Suryavarman I (1002 - 1050) brought unity to the Khmer kingdom, which reached its apogee under Suryavarman II (1113-1150). The empire was stretched out over most of Thailand, Laos, Cambodia and current South Vietnam.
Until the 11th century, Hinduism was the state religion and one of the main tasks of the king was building temples. Not only for themselves but also to honor the ancestors. In addition, they had extensive irrigation systems constructed. Suryavarman II built Angkor Wat, dedicated to the god Vishnu and the largest of more than 700 temples built by the Khmer kings.
In 1181 Jayavarman VII came to the throne. He introduced Buddhism and carried out many building projects. The new capital now called Angkor Thom (literally: "Great City") was built. Like the Roman emperors, he maintained a system of roads between his capital and provincial towns. Often, quality suffered for the sake of size and rapid construction, as is revealed in the intriguing but poorly constructed Bayon.
All those works consumed not only large sums of money but also a lot of workers, who could not be used as soldiers in order to withstand external attacks.
After the death of Jayavarman VII, under his son Indravarman II (reigned 1219–1243), the Khmer empire weakened. Under mounting pressure from increasingly powerful Dai Viet, the Khmer withdrew from many of the provinces in the east. In the west, the Thai subjects rebelled and established the first Thai kingdom at Sukhothai, further pushing back the Khmer.
In their third invasion the Siamese in 1413 occupied Angkor. The Khmer sought refuge in an area around current day Phnom Penh, which in 1772 also was conquered by the Siamese and burned. Oudong (40 km north of Phnom Penh) was capital for some time. Until 1864, Cambodia was in fact a vassal state of Siam and Vietnam alternately. The Vietnamese conquered the Mekong Delta, berefting Phnom Penh of a direct connection to the sea.
The University of Sydney has made a beautiful, very informative, animated time map of the Khmer Empire (from the year 100 to 1550).
That Cambodia still exists is thanks to the French, who in 1864 made it a French protectorate at the request of King Norodom.
Initially, the French had little interest in the country, but in 1884 they forced King Norodom to sign a treaty that Cambodia was in fact a French colony. They drew Cambodia into the French-controlled Indochinese Union. For nearly a century, the French exploited Cambodia commercially, and demanded power over politics, economics, and social life.
In 1907, the French made sure Siam returned the northwestern provinces of Battambang and Siem Reap back to Cambodian rule. You can see this depicted in a statue at Wat Phnom in Phnom Penh: King Sisowath receiving the two provinces (and Preah Vihear, returned in 1904).
Battambang and Siem Reap were lost again during the Japanese occupation in World War II. Only in 1947 were those areas given back to Cambodia again.
Further reading: see Modern Politics
A statue at Wat Phnom in Phnom Penh depicting King Sisowath receiving Battambang,
Siem Reap and Preah Vihear back from the Thais.