Research into the beginnings of food production in Africa has shown that the intensive use of cereals and experimentation with crops began at a rather early date, maybe as far back as the 16th millennium BC in Upper Egypt and Nubia. The best-documented example is a Wadi Kubbaniya where there is evidence of the earliest instances of plant cultivation anywhere in the world, confirming that this was a native African achievement. Food production was generally not practiced in North Africa before about the 5th millennium BC. Most of the indigenous species such as finger and bulrush millet, sorghum, yams, African rice, teff, enset, and noog were brought under cultivation between the 4th and 2nd millennia BC. South of the Equator the advent of food production did not occur before the beginnings of the Iron Age.