HistoryA depiction of an onager-drawn carts on the Sumerian "battle standard of Ur" (circa 2500 BCE)
Evidence of wheeled vehicles appears from the mid 4th millennium BCE, near-simultaneously in Mesopotamia, the Northern Caucasus (Maykop culture) and Central Europe, and so the question of which culture originally invented the wheeled vehicle remains unresolved and under debate. The earliest well-dated depiction of a wheeled vehicle (here a wagon—four wheels, two axles), is on the Bronocice pot, a ca. 3500–3350 BCE clay pot excavated in a Funnelbeaker culture settlement in southern Poland.
The wheeled vehicle from the area of its first occurrence (Mesopotamia, Caucasus, Balkans, Central Europe) spread across Eurasia, reaching the Indus Valley by the 3rd millennium BCE. During the 2nd millennium BCE, the spoke-wheeled chariot spread at an increased pace, reaching both China and Scandinavia by 1200 BCE. In China, the wheel was certainly present with the adoption of the chariot in ca. 1200 BCE, although Barbieri-Low (2000) argues for earlier Chinese wheeled vehicles, circa 2000 BCE.
Although they did not develop the wheel proper, the Olmec and certain other western hemisphere cultures seem to have approached it, as wheel-like worked stones have been found on objects identified as children's toys dating to about 1500 BCE. Early antiquity Nubians used wheels for spinning pottery and waterwheels. It is thought that Nubian waterwheels may have been ox-driven It is also known that Nubians used horse-driven chariots imported from Egypt.
The invention of the wheel thus falls in the late Neolithic, and may be seen in conjunction with the other technological advances that gave rise to the early Bronze Age. Note that this implies the passage of several wheel-less millennia even after the invention of agriculture and of pottery:
Wide usage of the wheel was probably delayed because smooth roads were needed for wheels to be effective. Carrying goods on the back would have been the preferred method of transportation over surfaces that contained many obstacles. The lack of developed roads prevented wide adoption of the wheel for transportation until well into the 20th century in less developed areas.
Early wheels were simple wooden disks with a hole for the axle. Because of the structure of wood a horizontal slice of a trunk is not suitable, as it does not have the structural strength to support weight without collapsing; rounded pieces of longitudinal boards are required.
The spoked wheel was invented more recently, and allowed the construction of lighter and swifter vehicles. The earliest known examples are in the context of the Andronovo culture, dating to ca 2000 BCE. Soon after this, horse cultures of the Caucasus region used horse-drawn spoked-wheel war chariots for the greater part of three centuries. They moved deep into the Greek peninsula where they joined with the existing Mediterranean peoples to give rise, eventually, to classical Greece after the breaking of Minoan dominance and consolidations led by pre-classical Sparta and Athens. Celtic chariots introduced an iron rim around the wheel in the 1st millennium BCE. The spoked wheel had been in continued use without major modification until the 1870s, when wire wheels and pneumatic tires were invented.
The invention of the wheel has also been important for technology in general, important applications including the water wheel, the cogwheel (see also antikythera mechanism), the spinning wheel, and the astrolabe or torquetum. More modern descendants of the wheel include the propeller, the jet engine, the flywheel (gyroscope) and the turbine.