While the first Dutch windmills appeared in the 13th century for grinding grain, their role became revolutionary in the 15th century when they were adapted to drain the wetlands. By using wind power to pump water out of low-lying areas, known as polders, the Dutch were able to reclaim vast amounts of land from the sea, literally "creating" much of the modern Netherlands. At the height of their use in the 18th and 19th centuries, over 9,000 windmills dotted the landscape, functioning as the engines of the Dutch Golden Age. In additional to water management, windmills were used to saw timber for shipbuilding, crush seeds for oil, and process paper and paint pigments.