During the Neolithic period (circa 8000–2000 B.C.E.), earthenware vessels were made by stacking coils of clay on top of one another to give each vessel its desired shape; the joins and surfaces were then smoothed with paddles and scrapers. Ritual pots, such as these three storage jars, would have been painted with mineral pigments mixed with slip and then burnished to create a shiny surface, unlike a utilitarian pot without decoration. By about 3000 B.C.E., the undulating lines and fluid contours of the painted decoration indicate the use of a brush-like tool. Neolithic cultures were located along the valleys of the Yellow River (central and northern China) and the Yangzi River (southern and eastern China).