There exists sparse evidence for a Pleistocene human occupation of present-day 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, although their dating is unreliable. Some slight archaeological evidence shows communities of hunter-gatherers inhabited the region during Holocene: the most ancient archaeological discovery site in Cambodia is considered to be the cave of L’aang Spean, in Battambang Province, which belongs to the Hoabinhian period. Excavations in its lower layers produced a series of radiocarbon dates as of 6000 BC. Upper layers in the same site gave evidence of transition to Neolithic, containing the earliest dated earthenware ceramics in Cambodia
Archaeological records for the period between Holocene and Iron Age remain equally limited. A pivotal event in Cambodian prehistory was the slow penetration of the first rice farmers from the north, which began in the late 3rd millennium BC. The most curious prehistoric evidence in Cambodia are the various “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, but some of them possibly date from 2nd millennium BC.