Ethnographic, technological, and archeological research into the technological life of the Haya of northwestern Tanzania shows that these people and their forebears 1500-2000 years ago practiced a highly advanced Fe smelting technology based on preheating principles and, as a result, produced C steel. This sophisticated technology may have evolved as an adaptation to overexploited forest resources. These discoveries are significant for the history of Africa and the history of metallurgy. -- AATA