Wool has been harvested since ancient times to provide clothing and household coverings. The first sheep were brought into America in 1521. About 450 different breeds of domestic sheep are known. Wool is harvested from sheep by mechanical shearing or hand shearing and is separated by skilled sorters. After the wood is sorted, it is cleaned in a process known as wool scouring. In some countries the manufacturer must specify various origins of the wool used in making a woolen item.