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 Laang Spean, in Battambang Province, which belongs to the Hoabinhian period. Excavations in its lower layers produced a series of radiocarbon dates around 6000 BC. Upper layers in the same site gave evidence of transition to Neolithic, containing the earliest dated earthenware ceramics in Cambodia.