Oolong tea has a very long and rich history. Its origins are said to go back over 1,000 years to the Beiyun region in the Fujian Province in China. Unlike black teas that are fully oxidized or green teas that undergo no oxidation, Oolong is formed through a special technique that results in the tea's partial oxidation. After withering, the tea is placed in muslin sacks and gently rolled. This bruises the leaf slightly, causing some oxidation to occur. This is repeated several times until the tea leaf turns darker green or reddish in appearance.