[citation needed] One of the most striking things about the Early Iron Age pots and smelting furnaces is that some of them were discovered at sites that the local people still associate with royalty, and still more significant is the continuity of language.
It underwent its greatest period of expansion, allied to an important metalworking activity, from the first to the sixth century A.D. and covered the Kivu region (in the Democratic Republic of the Congo) to the west up to Uganda, Rwanda, and Burundi in north-west Tanzania and south-west Kenya.
[citation needed] Research into early Iron Age civilisations in sub-Saharan Africa has been undertaken concurrently with studies on Niger–Congo linguistics on Bantu expansion.
meaning "frying pan" probably serving as a clue to a change in cooking techniques reflecting adaptation to a more sedentary lifestyle when Bantu-speaking people began to settle in the Rwanda and Burundi hills.
The ironsmelting furnace associated to these Urewe ceramics comprised a basin filled with fresh green leafy branches and herbs which served as a filter for the slag deposit at the base.
Environmental studies combine the tree species identification of charcoal collected from iron smelting furnaces and open hearths, palynological analyses of high altitude and valley peat bogs as well as in archaeological structures as well as phyto-sociological and geomorphologic data.
Those members of the Urewe civilisation who settled in Rwanda and Burundi did so exclusively in the hills region (central plain) in a 1700 and 1300 meters high zone on clay soils on primary substrate which are some of Africa's richest.
On the contrary, the impact of human activity, combined with consecutive periods of hot, dry climatic conditions have only served to aggravate soil degradation up to modern times.
The authors and major institutions linked to research into the Urewe civilisation in the Great Lakes region are: Mary Leakey (Owen collection published in 1948), Jean Hiernaux (excavations and publications 1960–70), Merrick Posnansky (excavations and publications 1960–70), David Phillipson (Synthesis of the Early Iron Age in Eastern Africa in 1976), the British Institute in Eastern Africa (BIEA), in Nairobi, under the aegis of J.E.G.