Carbon 14 dating of a cave at Laang Spean in northwest Cambodia reveals stone tools from 6000-7000 BCE [1], and pottery from 4200 BCE .[2] Further archaeological evidence indicates that other parts of the region now called Cambodia were inhabited from around 2000-1000 BCE by a Neolithic culture. Skulls and human bones found at Samrong Sen date from 1500 BCE.[2] These people may have migrated from South Eastern China to the Indochinese Peninsula. Scholars trace the first cultivation of rice and the first bronze making in Southeast Asia to these people.[2] By the 1st century CE, the inhabitants had developed relatively stable, organized societies and spoke languages very much related to the Cambodian or Khmer of the present day.[2] The culture and technical skills of these people in the 1st century CE far surpassed the primitive stage. The most advanced groups lived along the coast and in the lower Mekong River valley and delta regions in houses constructed on stilts where they cultivated rice, fished and kept domesticated animals. Recent research has unlocked the discovery of artificial circular earthworks dating to Cambodia's Neolithic era.*

The Khmer people were among the first inhabitants of South East Asia. They were also among the first in South East Asia to adopt religious ideas and political institutions from India and to establish centralized kingdoms comprising large territories. The earliest known kingdom in the area, Funan, flourished from around the first to the 6th century. This was succeeded by Chenla, which controlled large parts of modern Cambodia, Vietnam, Laos, and Thailand.

People have been living within the area covered by the present-day country of Cambodia at least since the 5th millennium BCE. The ancient Kingdom of Funan occupied a wider area, and it was during that period that the culture became heavily influenced by Hinduism. The state of Chenla then arose. The Khmer Empire had its golden age in the 9th to the 13th centuries, when huge temple complexes were built, most notably Angkor Wat.

The empire reached its greatest extent under the rule of Fan Shih-man in the early 3rd century, extending as far south as Malaysia and as far west as Burma. The Funanese established a strong system of mercantilism and commercial monopolies that would become a pattern for empires in the region. Exports from the Funan Empire were largely forest products and precious metals—including accessories such as gold elephants, ivory, rhinoceros horn, kingfisher feathers, wild spices like cardamom, lacquer hides and aromatic wood.[3] Fan Shih-man expanded the fleet and improved the Funanese bureaucracy, creating a quasi-feudal pattern that left local customs and identities largely intact, particularly in the empire's farther reaches.

The Funanese Empire rose to eminence from its affluent and powerful home city of Oc Eo (in nowadays Vietnam), known in the Roman Empire as Kattigara, meaning the Renowned City. Contacts with the distant Roman Empire are evidenced by the fact that Roman coins have been found at archeological sites dating from the 2nd and 3rd centuries.[3] However, most of the foreign trade of the Funan Empire was carried on much closer to home with India, especially the Bengal area of India. Trade with India commenced well before 500 BCE (before the widespread use of Sanskrit as a language in India).[4] With the Indian trade came the Indianization of the culture of Funan and the religion of Hinduism. Hinduism produced a syncretism phenomenon with other previous religions and beliefs already present in the Khmer culture. Funan and its succeeding societies which occupied this section of Southeast Asia would remain mainly Hindu in religion for about 900 years. Some cultural features and customs of Hinduism continue to exist within the current society.

Spanish and Portuguese missionaries visited from the 16th century, and Cambodia became a protectorate of France in the 19th century, being ruled as part of French Indochina. Cambodia became an independent kingdom in 1953 under Sihanouk. The Vietnam War extended into Cambodia, giving rise to the Khmer Rouge, which took Phnom Penh in 1975 and carried out a campaign of mass killing. Following an invasion by Vietnam, the Khmer Rouge were deposed and the People's Republic of Kampuchea was established. After years of isolation, the war-ravaged nation was reunited under the monarchy in 1993 and has seen rapid economic progress while rebuilding from decades of civil war.