The invention of the wheel and axle

Archaeological evidence for wheels used in transport appears around the late fourth millennium BCE, but the exact place where the wheel was invented remains uncertain. A key innovation was not simply a round part, but a carefully fitted system of wheel, axle, and platform that could carry a load on a cart. Such carts made it easier to move heavy goods and people, although wood rarely survives, so the earliest known finds are not necessarily the first wheels people made.