The history of the compass extends back for more than 2000 years. The first compasses were made of lodestone, a naturally magnetized ore of iron, in Han dynasty China between 300 and 200 BC. The compass was later used for navigation by the Song Dynasty. Later compasses were made of iron needles, magnetized by striking them with a lodestone. Dry compasses begin appearing around 1300 in Medieval Europe. This was supplanted in the early 20th century by the liquid-filled magnetic compass.