The time and place of the invention of the wheel + axle*, as a means of making transport easier, is disputed.

The oldest indirect evidence of wheeled movement was found in the form of miniature clay wheels north of the Black Sea before 4000 B.C., ^{[citation needed]} but some scholars put the invention earlier - attributed to either :

• The Halaf culture of BCE 6500 - 5100 BCE
• The Mesopotamian civilisation around 10,000 BC.

But there is currently no solid agreement on their first use.

The place and time of an "invention" of the wheel remains unclear, because the oldest hints do not guarantee the existence of real wheeled transport, or are dated with too much scatter.

Source : Wikipedia

Note: Some researchers think the the potter's wheel may have been invented before the transport wheel.

* Editor's note : It seems probable that the use of rounded objects to help move heavy objects by rolling (logs, pebbles etc), would have pre-dated the invention of perforated wheels attached to an axle.