Oldowan tools are named after Olduvai Gorge in Tanzania, where Oldowan tools were first found. The archaeologist Louis Leakey made this discovery in the 1930s. For a long time after that, archaeologists thought that the Oldowan were the earliest tools ever made. Now they know that hominids made stone tools much earlier in history - about 3.3 million years ago. This was before the genus "Homo" had evolved.