Windmill | Definition, History, Types, & Facts | Britannica
The earliest-known references to windmills are to a Persian millwright in ad 644 and to windmills in Seistan, Persia, in ad 915. These windmills are of the horizontal-mill type, with sails radiating from a vertical axis standing in a fixed building, which has openings for the inlet and outlet of the wind diametrically opposite to each other.