Medieval pottery started during the 6th century AD with simple/basic designs which were handmade. They were usually produced by those who would then use the vessels for cooking or storage, hence the plain designs. The pottery evolved to items that were glazed and decorated due to the technical advances which peaked by the 15th century AD. The handmade (rather than wheel made) pottery is very coarse as it often included pieces of stone. One of the reasons being that it allowed the pottery to withstand the temperatures when used over a fire for cooking. Although there are influences on pottery styles from different cultures, certain characteristics can be traced to specific regions. A popular technique involved pressing down with thumb marks around the base to steady the vessel. There were varying levels ranging from a few marks to a continuous series encompassing the piece.