The pre-colonial history of the modern-day Democratic Republic of the Congo encompasses the history of the Congo Basin region up to the establishment of European colonial rule in the era of New Imperialism and particularly the creation of the Congo Free State and its expansion into the interior after 1885. As the modern territorial boundaries of the Democratic Republic of the Congo did not exist in this period, it is inseparable from the wider pre-colonial histories of Central Africa, the Great Lakes and Rift Valley as well as the Atlantic World and Swahili coast. The current territory of the Democratic Republic of Congo was occupied by humans in the Paleolithic at least 80,000 years ago. Waves of Bantu migrations from 2000 BC to 500 AD moved into the basin from the northwest and covered the precolonial states absorbed or overthrown by the colonial powers. The Bantu migrations added to and displaced the indigenous Pygmy populations in the southern regions of the modern Congo states. The Bantu imported agriculture and iron-working techniques from West Africa into the area, as well as establishing the Bantu language family as the primary set of tongues for the Congolese. Subsequent migrations from the Darfur and Kurdufan regions of Sudan into the north of Congo, as well as East Africans migrating into the eastern Congo, added to the mix of ethnic groups. Paleolithic The area now known as the Democratic Republic of the Congo was populated as early as 90,000 years ago, as shown by the 1988 discovery of the Semliki harpoon at Katanda, one of the oldest barbed harpoons ever found, and which is believed to have been used to catch giant river catfish. In 1960 the Ishango bone tool was discovered, fashioned from the fibula of a baboon with a sharp piece of quartz affixed to one end, perhaps for engraving. It was first thought to be a tally stick, as it has a series of what has been interpreted as tally marks carved in three columns running the length of the tool, but some scientists have suggested that the groupings of the notches indicate a mathematical understanding that goes beyond counting. It is now believed to be more than 20,000 years old. Bantu migration The Bantu expansion is thought to have reached modern day DRC as well as Northern Angola and Zambia possibly as early as 500 BC, and then gradually started to