There exists evidence for a Pleistocene human occupation of what later is Cambodia, which includes quartz and quartzite pebble tools found in terraces along the Mekong River, in Stung Treng and Kratié provinces, and in Kampot province.[26] Some archaeological evidence shows communities of hunter-gatherers inhabited the region during the Holocene: the most ancient archaeological discovery site in Cambodia is considered to be the cave of Laang Spean, which belongs to the Hoabinhian period. Excavations in its lower layers produced a series of radiocarbon dates around 6000 BC.[26][27] Upper layers in the same site gave evidence of transition to Neolithic, containing the earliest dated earthenware ceramics in Cambodia.[28] Archaeological records for the period between the Holocene and Iron Age remain equally limited. An event in prehistory was the penetration of the first rice farmers from the north, which began in the third millennium BC.[29] Prehistoric evidence are the "circular earthworks" discovered in the red soils near Memot and in the adjacent region of Vietnam in the latter 1950s. Their function and age are still debated, and some of them possibly date from the second millennium BC.[30][31] Other prehistoric sites of somewhat uncertain date are Samrong Sen (not far from the ancient capital of Oudong), where the first investigations began in 1875,[32] and Phum Snay, in the northern province of Banteay Meanchey.[33] Iron was worked by about 500 BC, with supporting evidence coming from the Khorat Plateau, in what later is Thailand. In Cambodia, some Iron Age settlements were found beneath Baksei Chamkrong and other Angkorian temples while circular earthworks were discovered at the site of Lovea kilometres north-west of Angkor. Burials testify to improvement of food availability and trade, and the existence of a social structure and labour organisation.[34] Kinds of glass beads recovered from sites, such as the Phum Snay site in the northwest and the Prohear site in the southeast, suggest that there were two main trading networks at the time. The two networks were separated by time and space, which indicate that there was a shift from one network to the other at about the 2nd–4th century AD, probably due to changes in socio-political powers.[34] Pre-Angkorian, Angkorian, and Post-Angkor Main articles: Kingdom of Funan, Chenla, Khmer Empire, and Post-Angkor Period .mw-parser-output .tmulti .multiimageinner{display:flex;flex-direction:column}.mw-parser-output .tmulti .trow{display:flex;flex-direction:row;clear:left;flex-wrap:wrap;width:100%;box-sizing:border-box}.mw-parser-output .tmulti .tsingle{margin:1px;float:left}.mw-parser-output .tmulti .theader{clear:both;font-weight:bold;text-align:center;align-self:center;background-color:transparent;width:100%}.mw-parser-output .tmulti .thumbcaption{background-color:transparent}.mw-parser-output .tmulti .text-align-left{text-align:left}.mw-parser-output .tmulti .text-align-right{text-align:right}.mw-parser-output .tmulti .text-align-center{text-align:center}@media all and (max-width:720px){.mw-parser-output .tmulti .thumbinner{width:100%!important;box-sizing:border-box;max-width:none!important;align-items:center}.mw-parser-output .tmulti .trow{justify-content:center}.mw-parser-output .tmulti .tsingle{float:none!important;max-width:100%!important;box-sizing:border-box;text-align:center}.mw-parser-output .tmulti .tsingle .thumbcaption{text-align:left}.mw-parser-output .tmulti .trow>.thumbcaption{text-align:center}}@media screen{html.skin-theme-clientpref-night .mw-parser-output .tmulti .multiimageinner span:not(.skin-invert-image):not(.skin-invert):not(.bg-transparent) img{background-color:white}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .tmulti .multiimageinner span:not(.skin-invert-image):not(.skin-invert):not(.bg-transparent) img{background-color:white}}Angkor WatFaces of Bodhisattva Avalokiteshvara at Prasat Bayon During the 3rd, 4th, and 5th centuries, the Indianised states of Funan and its successor, Chenla, coalesced in what later is Cambodia and southwestern Vietnam. For more than 2,000 years, what was to become Cambodia absorbed influences from India, passing them on to other Southeast Asian civilisations that later became Thailand and Laos.[35] The Khmer Empire grew out of the remnants of Chenla, becoming firmly established in 802 when Jayavarman II (reigned c. 790 – c. 835) declared independence from Java and proclaimed themselves a Devaraja. They and their followers instituted the cult of the God-king and began a series of conquests that formed an empire which flourished in the area from the 9th to the 15th centuries.[36] During the rule of Jayavarman VIII the Angkor empire was attacked by the Mongol army of Kublai Khan; the king was able to buy peace.[37] Around the 13th century, Theravada missionaries from Sri Lanka reintroduced Theravada Buddhism to Southeast Asia, having sent missionaries previously in the 1190s.[38][39] The religion spread and eventually displaced Hinduism and Mahayana Buddhism as the popular religion of Angkor; it was not the official state religion until 1295 when Indravarman III took power.[40] The Khmer Empire was Southeast Asia's largest empire during the 12th century. The empire's centre of power was Angkor, where a series of capitals were constructed during the empire's zenith. In 2007 an international team of researchers using satellite photographs and other modern techniques concluded that Angkor had been the largest pre-industrial city in the world with an urban sprawl of 2,980 square kilometres (1,151 square miles).[41] The city could have supported a population of up to 1 million people.[42] After a series of wars with neighbouring kingdoms, Angkor was sacked by the Ayutthaya Kingdom and abandoned in 1432 because of ecological failure and infrastructure breakdown.[43][44] A map of Indochina in 1760 The hill tribe people were "hunted incessantly and carried off as slaves by the Siamese (Thai), the Annamites (Vietnamese), and the Cambodians".[45][46] Formerly part of the Khmer Empire, the Mekong Delta had been controlled by the Vietnamese since 1698,[47] with King Chey Chettha II granting the Vietnamese permission to settle in the area decades before.[48] French colonisation In 1863, King Norodom signed a treaty of protection with France.[17] The protectorate of France period lasted until 1953, with a brief interruption while the kingdom was occupied by the Japanese empire from 1941 to 1945[49] and simultaneously existing as the puppet state of Kingdom of Kampuchea in 1945. Between 1874 and 1962, the total population increased from about 946,000 to 5.7 million.[50] After King Norodom's death in 1904, France manipulated the choice of king and Sisowath, Norodom's brother, was placed on the throne. The throne became vacant in 1941 with the death of Monivong, Sisowath's son, and France passed over Monivong's son, Monireth, feeling he was too independently minded. Instead, Norodom Sihanouk, a maternal grandson of King Sisowath was enthroned. The French thought young Sihanouk would be easy to control.[49] Under the reign of King Norodom Sihanouk, Cambodia gained independence from France on 9 November 1953.[49] Kingdom (1953–1970) Main article: Kingdom of Cambodia (1953–1970) In 1955, Sihanouk abdicated in favour of his father to participate in politics and was elected prime minister. Upon his father's death in 1960, Sihanouk again became head of state, taking the title of prince. As the Vietnam War progressed, Sihanouk adopted an official policy of neutrality in the Cold War. Sihanouk allowed the Vietnamese communists to use Cambodia as a sanctuary and a supply route for their arms and other aid to their armed forces fighting in South Vietnam. In December 1967 Washington Post journalist Stanley Karnow was told by Sihanouk that if the US wanted to bomb the Vietnamese communist sanctuaries, he would not object unless Cambodians were killed.[51]