The earliest inhabitants of the region are assigned to the Middle Pleistocene period (781,000 to 126,000 years ago) in the Rongram valley of Garo Hills. The Paleolithic sites, which used handaxe-cleaver tools, have affinities to the Abbevillio-Acheulean culture. Other Paleolithic sites include those in the Daphabum area of Lohit district in Arunachal Pradesh which used stone tools from metamorphic rocks. The cave-based Paleolithic sites at Khangkhui in Ukhrul, Manipur, are placed in the Late Pleistocene period. There exists evidence of a microlithic culture in the Rongram Valley of Garo Hills that lie between the neolithic layers and virgin soil. The microliths here were made of dolerite, unlike those from the rest of India. Shreds of crude hand-made pottery indicate that the microlithic people were hunters and food-gatherers. Early Neolithic cultures based on the unifacially flaked hand-axe in the Garo hills have developed in line with the Hoabinhian culture, and it is conjectured that this region was the contact point for the Indian and the Southeast Asian cultures. The Late neolithic cultures have affinities with the spread of the Mon Khmer speaking people from Malaysia and the Ayeyarwady valley and late neolithic developments in South China. Since these cultures have been dated to 4500–4000 BCE, the Assam sites are dated to approximately that period. These neolithic sites, though widely spread, are concentrated in the hills and high grounds, due possibly to the floods. These cultures performed shifting cultivation called "jhum", which is still practiced by some communities in the region. Some typical sites are Daojali Hading in Dima Hasao, Sarutaru in Kamrup district and Selbagiri in the Garo Hills. There exists no archaeological evidence of Copper-Bronze or Iron Age culture in the region. This might seem like an impossibility given that corresponding cultures have been discovered in Bengal as well as Southeast Asia. It can only be conjectured that metal age sites in the region exist but have not yet been discovered. Though the metal age seems to be missing in Assam, the Iron Age Megalithic culture of South India finds an echo in the rich megalithic culture in the region, which begins to appear earlier than the late second millennium BCE, and which continues till today among the Khasi and the Naga people.