Horizontal-axis windmills with vertical sails appeared in Sistan, in greater Persia, by the ninth century to grind grain and lift water. The European vertical-sail post mill emerged in the late twelfth century, the earliest documented example at Weedley in Yorkshire in 1185. Windmills milled grain, sawed timber and, crucially in the Low Countries, drained polders by driving scoop wheels. They gave wind-rich, water-poor regions a source of mechanical power independent of rivers.
The windmill extended mechanical power to flat, riverless landscapes and became central to land drainage and reclamation, especially in the Netherlands.