Meanwhile, humans were learning to harness other forms of energy. The earliest known use of wind power is the sailboat.[40] The earliest record of a ship under sail is shown on an Egyptian pot dating back to 3200 BC.[41] From prehistoric times, Egyptians probably used the power of the Nile annual floods to irrigate their lands, gradually learning to regulate much of it through purposely built irrigation channels and 'catch' basins. Similarly, the early peoples of Mesopotamia, the Sumerians, learned to use the Tigris and Euphrates rivers for much the same purposes. But more extensive use of wind and water.